@levxdao/zero-money/deployments/mainnet/solcInputs/fcea8fc9661d288ba0c4cfcbdd9fdac8.json

World’s first genuine zero-value currency

{
  "language": "Solidity",
  "sources": {
    "contracts/ZeroMoney.sol": {
      "content": "// SPDX-License-Identifier: WTFPL\n\npragma solidity 0.8.13;\n\nimport \"@openzeppelin/contracts/token/ERC20/ERC20.sol\";\nimport \"@openzeppelin/contracts/access/Ownable.sol\";\nimport \"@openzeppelin/contracts/utils/math/SafeCast.sol\";\nimport \"@openzeppelin/contracts/utils/cryptography/ECDSA.sol\";\n\n/// @dev A mintable ERC20 token that allows anyone to pay and distribute ZERO\n///  to token holders as dividends and allows token holders to withdraw their dividends.\n///  Reference: https://github.com/Roger-Wu/erc1726-dividend-paying-token/blob/master/contracts/DividendPayingToken.sol\ncontract ZeroMoney is ERC20, Ownable {\n    using SafeCast for uint256;\n    using SafeCast for int256;\n\n    // For more discussion about choosing the value of `magnitude`,\n    //  see https://github.com/ethereum/EIPs/issues/1726#issuecomment-472352728\n    uint256 public constant MAGNITUDE = 2**128;\n    uint256 public constant HALVING_PERIOD = 21 days;\n    uint256 public constant FINAL_ERA = 60;\n\n    address public signer;\n    uint256 public startedAt;\n    mapping(address => bool) public blacklisted;\n    mapping(address => bool) public claimed;\n\n    uint256 internal magnifiedDividendPerShare;\n\n    // About dividendCorrection:\n    // If the token balance of a `_user` is never changed, the dividend of `_user` can be computed with:\n    //   `dividendOf(_user) = dividendPerShare * balanceOf(_user)`.\n    // When `balanceOf(_user)` is changed (via minting/burning/transferring tokens),\n    //   `dividendOf(_user)` should not be changed,\n    //   but the computed value of `dividendPerShare * balanceOf(_user)` is changed.\n    // To keep the `dividendOf(_user)` unchanged, we add a correction term:\n    //   `dividendOf(_user) = dividendPerShare * balanceOf(_user) + dividendCorrectionOf(_user)`,\n    //   where `dividendCorrectionOf(_user)` is updated whenever `balanceOf(_user)` is changed:\n    //   `dividendCorrectionOf(_user) = dividendPerShare * (old balanceOf(_user)) - (new balanceOf(_user))`.\n    // So now `dividendOf(_user)` returns the same value before and after `balanceOf(_user)` is changed.\n    mapping(address => int256) internal magnifiedDividendCorrections;\n    mapping(address => uint256) internal withdrawnDividends;\n\n    event ChangeSigner(address indexed signer);\n    event SetBlacklisted(address indexed account, bool blacklisted);\n    event Start();\n    /// @dev This event MUST emit when ZERO is distributed to token holders.\n    /// @param weiAmount The amount of distributed ZERO in wei.\n    event DividendsDistributed(uint256 weiAmount);\n    /// @dev This event MUST emit when an address withdraws their dividend.\n    /// @param to The address which withdraws ZERO from this contract.\n    /// @param weiAmount The amount of withdrawn ZERO in wei.\n    event Withdraw(address indexed to, uint256 weiAmount);\n\n    constructor(address _signer) ERC20(\"thezero.money\", \"ZERO\") {\n        signer = _signer;\n        blacklisted[address(this)] = true;\n\n        emit ChangeSigner(_signer);\n        emit SetBlacklisted(address(this), true);\n    }\n\n    function currentHalvingEra() public view returns (uint256) {\n        if (startedAt == 0) return type(uint256).max;\n        uint256 era = (block.timestamp - startedAt) / HALVING_PERIOD;\n        return FINAL_ERA < era ? FINAL_ERA : era;\n    }\n\n    /// @notice View the amount of dividend in wei that an address can withdraw.\n    /// @param account The address of a token holder.\n    /// @return The amount of dividend in wei that `account` can withdraw.\n    function withdrawableDividendOf(address account) public view returns (uint256) {\n        return accumulativeDividendOf(account) - withdrawnDividends[account];\n    }\n\n    /// @notice View the amount of dividend in wei that an address has withdrawn.\n    /// @param account The address of a token holder.\n    /// @return The amount of dividend in wei that `account` has withdrawn.\n    function withdrawnDividendOf(address account) public view returns (uint256) {\n        return withdrawnDividends[account];\n    }\n\n    /// @notice View the amount of dividend in wei that an address has earned in total.\n    /// @dev accumulativeDividendOf(account) = withdrawableDividendOf(account) + withdrawnDividendOf(account)\n    /// = (magnifiedDividendPerShare * balanceOf(account) + magnifiedDividendCorrections[account]) / magnitude\n    /// @param account The address of a token holder.\n    /// @return The amount of dividend in wei that `account` has earned in total.\n    function accumulativeDividendOf(address account) public view returns (uint256) {\n        return\n            ((magnifiedDividendPerShare * balanceOf(account)).toInt256() + magnifiedDividendCorrections[account])\n            .toUint256() / MAGNITUDE;\n    }\n\n    function changeSigner(address _signer) external onlyOwner {\n        signer = _signer;\n\n        emit ChangeSigner(_signer);\n    }\n\n    function setBlacklisted(address account, bool _blacklisted) external onlyOwner {\n        blacklisted[account] = _blacklisted;\n\n        emit SetBlacklisted(account, _blacklisted);\n    }\n\n    function start() external onlyOwner {\n        _mint(msg.sender, totalSupply());\n        startedAt = block.timestamp;\n\n        emit Start();\n    }\n\n    function claim(\n        uint8 v,\n        bytes32 r,\n        bytes32 s\n    ) external {\n        require(!claimed[msg.sender], \"ZERO: CLAIMED\");\n\n        bytes32 message = keccak256(abi.encodePacked(msg.sender));\n        require(ECDSA.recover(ECDSA.toEthSignedMessageHash(message), v, r, s) == signer, \"ZERO: UNAUTHORIZED\");\n\n        claimed[msg.sender] = true;\n\n        _mint(msg.sender, 1 ether);\n    }\n\n    /// @dev Internal function that mints tokens to an account.\n    /// Update magnifiedDividendCorrections to keep dividends unchanged.\n    /// @param account The account that will receive the created tokens.\n    /// @param value The amount that will be created.\n    function _mint(address account, uint256 value) internal override {\n        super._mint(account, value);\n\n        magnifiedDividendCorrections[account] -= (magnifiedDividendPerShare * value).toInt256();\n    }\n\n    /// @dev Internal function that transfer tokens from one address to another.\n    /// Update magnifiedDividendCorrections to keep dividends unchanged.\n    /// @param from The address to transfer from.\n    /// @param to The address to transfer to.\n    /// @param amount The amount to be transferred.\n    function _transfer(\n        address from,\n        address to,\n        uint256 amount\n    ) internal override {\n        super._transfer(from, to, amount);\n\n        int256 _magCorrection = (magnifiedDividendPerShare * amount).toInt256();\n        magnifiedDividendCorrections[from] += _magCorrection;\n        magnifiedDividendCorrections[to] -= _magCorrection;\n\n        if (startedAt > 0 && !blacklisted[from]) {\n            _distributeDividends(amount);\n        }\n    }\n\n    /// @notice Distributes ZERO to token holders as dividends.\n    /// @dev It emits the `DividendsDistributed` event if the amount of received ZERO is greater than 0.\n    /// About undistributed ZERO:\n    ///   In each distribution, there is a small amount of ZERO not distributed,\n    ///     the magnified amount of which is\n    ///     `(msg.value * magnitude) % totalSupply()`.\n    ///   With a well-chosen `magnitude`, the amount of undistributed ZERO\n    ///     (de-magnified) in a distribution can be less than 1 wei.\n    ///   We can actually keep track of the undistributed ZERO in a distribution\n    ///     and try to distribute it in the next distribution,\n    ///     but keeping track of such data on-chain costs much more than\n    ///     the saved ZERO, so we don't do that.\n    function _distributeDividends(uint256 amount) private {\n        uint256 era = (block.timestamp - startedAt) / HALVING_PERIOD;\n        if (FINAL_ERA <= era) {\n            return;\n        }\n\n        amount = amount / (2**era);\n        magnifiedDividendPerShare += ((amount * MAGNITUDE) / totalSupply());\n        _mint(address(this), amount);\n        emit DividendsDistributed(amount);\n    }\n\n    /// @notice Withdraws dividends distributed to the sender.\n    /// @dev It emits a `Withdraw` event if the amount of withdrawn ZERO is greater than 0.\n    function withdrawDividend() public {\n        uint256 _withdrawableDividend = withdrawableDividendOf(msg.sender);\n        require(_withdrawableDividend > 0, \"ZERO: ZERO_DIVIDEND\");\n\n        withdrawnDividends[msg.sender] += _withdrawableDividend;\n        _transfer(address(this), msg.sender, _withdrawableDividend);\n        emit Withdraw(msg.sender, _withdrawableDividend);\n    }\n\n    /// @dev External function that burns an amount of the token of a given account.\n    /// Update magnifiedDividendCorrections to keep dividends unchanged.\n    /// @param value The amount that will be burnt.\n    function burn(uint256 value) public {\n        _burn(msg.sender, value);\n\n        magnifiedDividendCorrections[msg.sender] += (magnifiedDividendPerShare * value).toInt256();\n    }\n}\n"
    },
    "@openzeppelin/contracts/token/ERC20/ERC20.sol": {
      "content": "// SPDX-License-Identifier: MIT\n// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC20/ERC20.sol)\n\npragma solidity ^0.8.0;\n\nimport \"./IERC20.sol\";\nimport \"./extensions/IERC20Metadata.sol\";\nimport \"../../utils/Context.sol\";\n\n/**\n * @dev Implementation of the {IERC20} interface.\n *\n * This implementation is agnostic to the way tokens are created. This means\n * that a supply mechanism has to be added in a derived contract using {_mint}.\n * For a generic mechanism see {ERC20PresetMinterPauser}.\n *\n * TIP: For a detailed writeup see our guide\n * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How\n * to implement supply mechanisms].\n *\n * We have followed general OpenZeppelin Contracts guidelines: functions revert\n * instead returning `false` on failure. This behavior is nonetheless\n * conventional and does not conflict with the expectations of ERC20\n * applications.\n *\n * Additionally, an {Approval} event is emitted on calls to {transferFrom}.\n * This allows applications to reconstruct the allowance for all accounts just\n * by listening to said events. Other implementations of the EIP may not emit\n * these events, as it isn't required by the specification.\n *\n * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}\n * functions have been added to mitigate the well-known issues around setting\n * allowances. See {IERC20-approve}.\n */\ncontract ERC20 is Context, IERC20, IERC20Metadata {\n    mapping(address => uint256) private _balances;\n\n    mapping(address => mapping(address => uint256)) private _allowances;\n\n    uint256 private _totalSupply;\n\n    string private _name;\n    string private _symbol;\n\n    /**\n     * @dev Sets the values for {name} and {symbol}.\n     *\n     * The default value of {decimals} is 18. To select a different value for\n     * {decimals} you should overload it.\n     *\n     * All two of these values are immutable: they can only be set once during\n     * construction.\n     */\n    constructor(string memory name_, string memory symbol_) {\n        _name = name_;\n        _symbol = symbol_;\n    }\n\n    /**\n     * @dev Returns the name of the token.\n     */\n    function name() public view virtual override returns (string memory) {\n        return _name;\n    }\n\n    /**\n     * @dev Returns the symbol of the token, usually a shorter version of the\n     * name.\n     */\n    function symbol() public view virtual override returns (string memory) {\n        return _symbol;\n    }\n\n    /**\n     * @dev Returns the number of decimals used to get its user representation.\n     * For example, if `decimals` equals `2`, a balance of `505` tokens should\n     * be displayed to a user as `5.05` (`505 / 10 ** 2`).\n     *\n     * Tokens usually opt for a value of 18, imitating the relationship between\n     * Ether and Wei. This is the value {ERC20} uses, unless this function is\n     * overridden;\n     *\n     * NOTE: This information is only used for _display_ purposes: it in\n     * no way affects any of the arithmetic of the contract, including\n     * {IERC20-balanceOf} and {IERC20-transfer}.\n     */\n    function decimals() public view virtual override returns (uint8) {\n        return 18;\n    }\n\n    /**\n     * @dev See {IERC20-totalSupply}.\n     */\n    function totalSupply() public view virtual override returns (uint256) {\n        return _totalSupply;\n    }\n\n    /**\n     * @dev See {IERC20-balanceOf}.\n     */\n    function balanceOf(address account) public view virtual override returns (uint256) {\n        return _balances[account];\n    }\n\n    /**\n     * @dev See {IERC20-transfer}.\n     *\n     * Requirements:\n     *\n     * - `to` cannot be the zero address.\n     * - the caller must have a balance of at least `amount`.\n     */\n    function transfer(address to, uint256 amount) public virtual override returns (bool) {\n        address owner = _msgSender();\n        _transfer(owner, to, amount);\n        return true;\n    }\n\n    /**\n     * @dev See {IERC20-allowance}.\n     */\n    function allowance(address owner, address spender) public view virtual override returns (uint256) {\n        return _allowances[owner][spender];\n    }\n\n    /**\n     * @dev See {IERC20-approve}.\n     *\n     * NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on\n     * `transferFrom`. This is semantically equivalent to an infinite approval.\n     *\n     * Requirements:\n     *\n     * - `spender` cannot be the zero address.\n     */\n    function approve(address spender, uint256 amount) public virtual override returns (bool) {\n        address owner = _msgSender();\n        _approve(owner, spender, amount);\n        return true;\n    }\n\n    /**\n     * @dev See {IERC20-transferFrom}.\n     *\n     * Emits an {Approval} event indicating the updated allowance. This is not\n     * required by the EIP. See the note at the beginning of {ERC20}.\n     *\n     * NOTE: Does not update the allowance if the current allowance\n     * is the maximum `uint256`.\n     *\n     * Requirements:\n     *\n     * - `from` and `to` cannot be the zero address.\n     * - `from` must have a balance of at least `amount`.\n     * - the caller must have allowance for ``from``'s tokens of at least\n     * `amount`.\n     */\n    function transferFrom(\n        address from,\n        address to,\n        uint256 amount\n    ) public virtual override returns (bool) {\n        address spender = _msgSender();\n        _spendAllowance(from, spender, amount);\n        _transfer(from, to, amount);\n        return true;\n    }\n\n    /**\n     * @dev Atomically increases the allowance granted to `spender` by the caller.\n     *\n     * This is an alternative to {approve} that can be used as a mitigation for\n     * problems described in {IERC20-approve}.\n     *\n     * Emits an {Approval} event indicating the updated allowance.\n     *\n     * Requirements:\n     *\n     * - `spender` cannot be the zero address.\n     */\n    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {\n        address owner = _msgSender();\n        _approve(owner, spender, _allowances[owner][spender] + addedValue);\n        return true;\n    }\n\n    /**\n     * @dev Atomically decreases the allowance granted to `spender` by the caller.\n     *\n     * This is an alternative to {approve} that can be used as a mitigation for\n     * problems described in {IERC20-approve}.\n     *\n     * Emits an {Approval} event indicating the updated allowance.\n     *\n     * Requirements:\n     *\n     * - `spender` cannot be the zero address.\n     * - `spender` must have allowance for the caller of at least\n     * `subtractedValue`.\n     */\n    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {\n        address owner = _msgSender();\n        uint256 currentAllowance = _allowances[owner][spender];\n        require(currentAllowance >= subtractedValue, \"ERC20: decreased allowance below zero\");\n        unchecked {\n            _approve(owner, spender, currentAllowance - subtractedValue);\n        }\n\n        return true;\n    }\n\n    /**\n     * @dev Moves `amount` of tokens from `sender` to `recipient`.\n     *\n     * This internal function is equivalent to {transfer}, and can be used to\n     * e.g. implement automatic token fees, slashing mechanisms, etc.\n     *\n     * Emits a {Transfer} event.\n     *\n     * Requirements:\n     *\n     * - `from` cannot be the zero address.\n     * - `to` cannot be the zero address.\n     * - `from` must have a balance of at least `amount`.\n     */\n    function _transfer(\n        address from,\n        address to,\n        uint256 amount\n    ) internal virtual {\n        require(from != address(0), \"ERC20: transfer from the zero address\");\n        require(to != address(0), \"ERC20: transfer to the zero address\");\n\n        _beforeTokenTransfer(from, to, amount);\n\n        uint256 fromBalance = _balances[from];\n        require(fromBalance >= amount, \"ERC20: transfer amount exceeds balance\");\n        unchecked {\n            _balances[from] = fromBalance - amount;\n        }\n        _balances[to] += amount;\n\n        emit Transfer(from, to, amount);\n\n        _afterTokenTransfer(from, to, amount);\n    }\n\n    /** @dev Creates `amount` tokens and assigns them to `account`, increasing\n     * the total supply.\n     *\n     * Emits a {Transfer} event with `from` set to the zero address.\n     *\n     * Requirements:\n     *\n     * - `account` cannot be the zero address.\n     */\n    function _mint(address account, uint256 amount) internal virtual {\n        require(account != address(0), \"ERC20: mint to the zero address\");\n\n        _beforeTokenTransfer(address(0), account, amount);\n\n        _totalSupply += amount;\n        _balances[account] += amount;\n        emit Transfer(address(0), account, amount);\n\n        _afterTokenTransfer(address(0), account, amount);\n    }\n\n    /**\n     * @dev Destroys `amount` tokens from `account`, reducing the\n     * total supply.\n     *\n     * Emits a {Transfer} event with `to` set to the zero address.\n     *\n     * Requirements:\n     *\n     * - `account` cannot be the zero address.\n     * - `account` must have at least `amount` tokens.\n     */\n    function _burn(address account, uint256 amount) internal virtual {\n        require(account != address(0), \"ERC20: burn from the zero address\");\n\n        _beforeTokenTransfer(account, address(0), amount);\n\n        uint256 accountBalance = _balances[account];\n        require(accountBalance >= amount, \"ERC20: burn amount exceeds balance\");\n        unchecked {\n            _balances[account] = accountBalance - amount;\n        }\n        _totalSupply -= amount;\n\n        emit Transfer(account, address(0), amount);\n\n        _afterTokenTransfer(account, address(0), amount);\n    }\n\n    /**\n     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.\n     *\n     * This internal function is equivalent to `approve`, and can be used to\n     * e.g. set automatic allowances for certain subsystems, etc.\n     *\n     * Emits an {Approval} event.\n     *\n     * Requirements:\n     *\n     * - `owner` cannot be the zero address.\n     * - `spender` cannot be the zero address.\n     */\n    function _approve(\n        address owner,\n        address spender,\n        uint256 amount\n    ) internal virtual {\n        require(owner != address(0), \"ERC20: approve from the zero address\");\n        require(spender != address(0), \"ERC20: approve to the zero address\");\n\n        _allowances[owner][spender] = amount;\n        emit Approval(owner, spender, amount);\n    }\n\n    /**\n     * @dev Spend `amount` form the allowance of `owner` toward `spender`.\n     *\n     * Does not update the allowance amount in case of infinite allowance.\n     * Revert if not enough allowance is available.\n     *\n     * Might emit an {Approval} event.\n     */\n    function _spendAllowance(\n        address owner,\n        address spender,\n        uint256 amount\n    ) internal virtual {\n        uint256 currentAllowance = allowance(owner, spender);\n        if (currentAllowance != type(uint256).max) {\n            require(currentAllowance >= amount, \"ERC20: insufficient allowance\");\n            unchecked {\n                _approve(owner, spender, currentAllowance - amount);\n            }\n        }\n    }\n\n    /**\n     * @dev Hook that is called before any transfer of tokens. This includes\n     * minting and burning.\n     *\n     * Calling conditions:\n     *\n     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens\n     * will be transferred to `to`.\n     * - when `from` is zero, `amount` tokens will be minted for `to`.\n     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.\n     * - `from` and `to` are never both zero.\n     *\n     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].\n     */\n    function _beforeTokenTransfer(\n        address from,\n        address to,\n        uint256 amount\n    ) internal virtual {}\n\n    /**\n     * @dev Hook that is called after any transfer of tokens. This includes\n     * minting and burning.\n     *\n     * Calling conditions:\n     *\n     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens\n     * has been transferred to `to`.\n     * - when `from` is zero, `amount` tokens have been minted for `to`.\n     * - when `to` is zero, `amount` of ``from``'s tokens have been burned.\n     * - `from` and `to` are never both zero.\n     *\n     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].\n     */\n    function _afterTokenTransfer(\n        address from,\n        address to,\n        uint256 amount\n    ) internal virtual {}\n}\n"
    },
    "@openzeppelin/contracts/access/Ownable.sol": {
      "content": "// SPDX-License-Identifier: MIT\n// OpenZeppelin Contracts v4.4.1 (access/Ownable.sol)\n\npragma solidity ^0.8.0;\n\nimport \"../utils/Context.sol\";\n\n/**\n * @dev Contract module which provides a basic access control mechanism, where\n * there is an account (an owner) that can be granted exclusive access to\n * specific functions.\n *\n * By default, the owner account will be the one that deploys the contract. This\n * can later be changed with {transferOwnership}.\n *\n * This module is used through inheritance. It will make available the modifier\n * `onlyOwner`, which can be applied to your functions to restrict their use to\n * the owner.\n */\nabstract contract Ownable is Context {\n    address private _owner;\n\n    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);\n\n    /**\n     * @dev Initializes the contract setting the deployer as the initial owner.\n     */\n    constructor() {\n        _transferOwnership(_msgSender());\n    }\n\n    /**\n     * @dev Returns the address of the current owner.\n     */\n    function owner() public view virtual returns (address) {\n        return _owner;\n    }\n\n    /**\n     * @dev Throws if called by any account other than the owner.\n     */\n    modifier onlyOwner() {\n        require(owner() == _msgSender(), \"Ownable: caller is not the owner\");\n        _;\n    }\n\n    /**\n     * @dev Leaves the contract without owner. It will not be possible to call\n     * `onlyOwner` functions anymore. Can only be called by the current owner.\n     *\n     * NOTE: Renouncing ownership will leave the contract without an owner,\n     * thereby removing any functionality that is only available to the owner.\n     */\n    function renounceOwnership() public virtual onlyOwner {\n        _transferOwnership(address(0));\n    }\n\n    /**\n     * @dev Transfers ownership of the contract to a new account (`newOwner`).\n     * Can only be called by the current owner.\n     */\n    function transferOwnership(address newOwner) public virtual onlyOwner {\n        require(newOwner != address(0), \"Ownable: new owner is the zero address\");\n        _transferOwnership(newOwner);\n    }\n\n    /**\n     * @dev Transfers ownership of the contract to a new account (`newOwner`).\n     * Internal function without access restriction.\n     */\n    function _transferOwnership(address newOwner) internal virtual {\n        address oldOwner = _owner;\n        _owner = newOwner;\n        emit OwnershipTransferred(oldOwner, newOwner);\n    }\n}\n"
    },
    "@openzeppelin/contracts/utils/math/SafeCast.sol": {
      "content": "// SPDX-License-Identifier: MIT\n// OpenZeppelin Contracts v4.4.1 (utils/math/SafeCast.sol)\n\npragma solidity ^0.8.0;\n\n/**\n * @dev Wrappers over Solidity's uintXX/intXX casting operators with added overflow\n * checks.\n *\n * Downcasting from uint256/int256 in Solidity does not revert on overflow. This can\n * easily result in undesired exploitation or bugs, since developers usually\n * assume that overflows raise errors. `SafeCast` restores this intuition by\n * reverting the transaction when such an operation overflows.\n *\n * Using this library instead of the unchecked operations eliminates an entire\n * class of bugs, so it's recommended to use it always.\n *\n * Can be combined with {SafeMath} and {SignedSafeMath} to extend it to smaller types, by performing\n * all math on `uint256` and `int256` and then downcasting.\n */\nlibrary SafeCast {\n    /**\n     * @dev Returns the downcasted uint224 from uint256, reverting on\n     * overflow (when the input is greater than largest uint224).\n     *\n     * Counterpart to Solidity's `uint224` operator.\n     *\n     * Requirements:\n     *\n     * - input must fit into 224 bits\n     */\n    function toUint224(uint256 value) internal pure returns (uint224) {\n        require(value <= type(uint224).max, \"SafeCast: value doesn't fit in 224 bits\");\n        return uint224(value);\n    }\n\n    /**\n     * @dev Returns the downcasted uint128 from uint256, reverting on\n     * overflow (when the input is greater than largest uint128).\n     *\n     * Counterpart to Solidity's `uint128` operator.\n     *\n     * Requirements:\n     *\n     * - input must fit into 128 bits\n     */\n    function toUint128(uint256 value) internal pure returns (uint128) {\n        require(value <= type(uint128).max, \"SafeCast: value doesn't fit in 128 bits\");\n        return uint128(value);\n    }\n\n    /**\n     * @dev Returns the downcasted uint96 from uint256, reverting on\n     * overflow (when the input is greater than largest uint96).\n     *\n     * Counterpart to Solidity's `uint96` operator.\n     *\n     * Requirements:\n     *\n     * - input must fit into 96 bits\n     */\n    function toUint96(uint256 value) internal pure returns (uint96) {\n        require(value <= type(uint96).max, \"SafeCast: value doesn't fit in 96 bits\");\n        return uint96(value);\n    }\n\n    /**\n     * @dev Returns the downcasted uint64 from uint256, reverting on\n     * overflow (when the input is greater than largest uint64).\n     *\n     * Counterpart to Solidity's `uint64` operator.\n     *\n     * Requirements:\n     *\n     * - input must fit into 64 bits\n     */\n    function toUint64(uint256 value) internal pure returns (uint64) {\n        require(value <= type(uint64).max, \"SafeCast: value doesn't fit in 64 bits\");\n        return uint64(value);\n    }\n\n    /**\n     * @dev Returns the downcasted uint32 from uint256, reverting on\n     * overflow (when the input is greater than largest uint32).\n     *\n     * Counterpart to Solidity's `uint32` operator.\n     *\n     * Requirements:\n     *\n     * - input must fit into 32 bits\n     */\n    function toUint32(uint256 value) internal pure returns (uint32) {\n        require(value <= type(uint32).max, \"SafeCast: value doesn't fit in 32 bits\");\n        return uint32(value);\n    }\n\n    /**\n     * @dev Returns the downcasted uint16 from uint256, reverting on\n     * overflow (when the input is greater than largest uint16).\n     *\n     * Counterpart to Solidity's `uint16` operator.\n     *\n     * Requirements:\n     *\n     * - input must fit into 16 bits\n     */\n    function toUint16(uint256 value) internal pure returns (uint16) {\n        require(value <= type(uint16).max, \"SafeCast: value doesn't fit in 16 bits\");\n        return uint16(value);\n    }\n\n    /**\n     * @dev Returns the downcasted uint8 from uint256, reverting on\n     * overflow (when the input is greater than largest uint8).\n     *\n     * Counterpart to Solidity's `uint8` operator.\n     *\n     * Requirements:\n     *\n     * - input must fit into 8 bits.\n     */\n    function toUint8(uint256 value) internal pure returns (uint8) {\n        require(value <= type(uint8).max, \"SafeCast: value doesn't fit in 8 bits\");\n        return uint8(value);\n    }\n\n    /**\n     * @dev Converts a signed int256 into an unsigned uint256.\n     *\n     * Requirements:\n     *\n     * - input must be greater than or equal to 0.\n     */\n    function toUint256(int256 value) internal pure returns (uint256) {\n        require(value >= 0, \"SafeCast: value must be positive\");\n        return uint256(value);\n    }\n\n    /**\n     * @dev Returns the downcasted int128 from int256, reverting on\n     * overflow (when the input is less than smallest int128 or\n     * greater than largest int128).\n     *\n     * Counterpart to Solidity's `int128` operator.\n     *\n     * Requirements:\n     *\n     * - input must fit into 128 bits\n     *\n     * _Available since v3.1._\n     */\n    function toInt128(int256 value) internal pure returns (int128) {\n        require(value >= type(int128).min && value <= type(int128).max, \"SafeCast: value doesn't fit in 128 bits\");\n        return int128(value);\n    }\n\n    /**\n     * @dev Returns the downcasted int64 from int256, reverting on\n     * overflow (when the input is less than smallest int64 or\n     * greater than largest int64).\n     *\n     * Counterpart to Solidity's `int64` operator.\n     *\n     * Requirements:\n     *\n     * - input must fit into 64 bits\n     *\n     * _Available since v3.1._\n     */\n    function toInt64(int256 value) internal pure returns (int64) {\n        require(value >= type(int64).min && value <= type(int64).max, \"SafeCast: value doesn't fit in 64 bits\");\n        return int64(value);\n    }\n\n    /**\n     * @dev Returns the downcasted int32 from int256, reverting on\n     * overflow (when the input is less than smallest int32 or\n     * greater than largest int32).\n     *\n     * Counterpart to Solidity's `int32` operator.\n     *\n     * Requirements:\n     *\n     * - input must fit into 32 bits\n     *\n     * _Available since v3.1._\n     */\n    function toInt32(int256 value) internal pure returns (int32) {\n        require(value >= type(int32).min && value <= type(int32).max, \"SafeCast: value doesn't fit in 32 bits\");\n        return int32(value);\n    }\n\n    /**\n     * @dev Returns the downcasted int16 from int256, reverting on\n     * overflow (when the input is less than smallest int16 or\n     * greater than largest int16).\n     *\n     * Counterpart to Solidity's `int16` operator.\n     *\n     * Requirements:\n     *\n     * - input must fit into 16 bits\n     *\n     * _Available since v3.1._\n     */\n    function toInt16(int256 value) internal pure returns (int16) {\n        require(value >= type(int16).min && value <= type(int16).max, \"SafeCast: value doesn't fit in 16 bits\");\n        return int16(value);\n    }\n\n    /**\n     * @dev Returns the downcasted int8 from int256, reverting on\n     * overflow (when the input is less than smallest int8 or\n     * greater than largest int8).\n     *\n     * Counterpart to Solidity's `int8` operator.\n     *\n     * Requirements:\n     *\n     * - input must fit into 8 bits.\n     *\n     * _Available since v3.1._\n     */\n    function toInt8(int256 value) internal pure returns (int8) {\n        require(value >= type(int8).min && value <= type(int8).max, \"SafeCast: value doesn't fit in 8 bits\");\n        return int8(value);\n    }\n\n    /**\n     * @dev Converts an unsigned uint256 into a signed int256.\n     *\n     * Requirements:\n     *\n     * - input must be less than or equal to maxInt256.\n     */\n    function toInt256(uint256 value) internal pure returns (int256) {\n        // Note: Unsafe cast below is okay because `type(int256).max` is guaranteed to be positive\n        require(value <= uint256(type(int256).max), \"SafeCast: value doesn't fit in an int256\");\n        return int256(value);\n    }\n}\n"
    },
    "@openzeppelin/contracts/utils/cryptography/ECDSA.sol": {
      "content": "// SPDX-License-Identifier: MIT\n// OpenZeppelin Contracts (last updated v4.5.0) (utils/cryptography/ECDSA.sol)\n\npragma solidity ^0.8.0;\n\nimport \"../Strings.sol\";\n\n/**\n * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.\n *\n * These functions can be used to verify that a message was signed by the holder\n * of the private keys of a given address.\n */\nlibrary ECDSA {\n    enum RecoverError {\n        NoError,\n        InvalidSignature,\n        InvalidSignatureLength,\n        InvalidSignatureS,\n        InvalidSignatureV\n    }\n\n    function _throwError(RecoverError error) private pure {\n        if (error == RecoverError.NoError) {\n            return; // no error: do nothing\n        } else if (error == RecoverError.InvalidSignature) {\n            revert(\"ECDSA: invalid signature\");\n        } else if (error == RecoverError.InvalidSignatureLength) {\n            revert(\"ECDSA: invalid signature length\");\n        } else if (error == RecoverError.InvalidSignatureS) {\n            revert(\"ECDSA: invalid signature 's' value\");\n        } else if (error == RecoverError.InvalidSignatureV) {\n            revert(\"ECDSA: invalid signature 'v' value\");\n        }\n    }\n\n    /**\n     * @dev Returns the address that signed a hashed message (`hash`) with\n     * `signature` or error string. This address can then be used for verification purposes.\n     *\n     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:\n     * this function rejects them by requiring the `s` value to be in the lower\n     * half order, and the `v` value to be either 27 or 28.\n     *\n     * IMPORTANT: `hash` _must_ be the result of a hash operation for the\n     * verification to be secure: it is possible to craft signatures that\n     * recover to arbitrary addresses for non-hashed data. A safe way to ensure\n     * this is by receiving a hash of the original message (which may otherwise\n     * be too long), and then calling {toEthSignedMessageHash} on it.\n     *\n     * Documentation for signature generation:\n     * - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]\n     * - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]\n     *\n     * _Available since v4.3._\n     */\n    function tryRecover(bytes32 hash, bytes memory signature) internal pure returns (address, RecoverError) {\n        // Check the signature length\n        // - case 65: r,s,v signature (standard)\n        // - case 64: r,vs signature (cf https://eips.ethereum.org/EIPS/eip-2098) _Available since v4.1._\n        if (signature.length == 65) {\n            bytes32 r;\n            bytes32 s;\n            uint8 v;\n            // ecrecover takes the signature parameters, and the only way to get them\n            // currently is to use assembly.\n            assembly {\n                r := mload(add(signature, 0x20))\n                s := mload(add(signature, 0x40))\n                v := byte(0, mload(add(signature, 0x60)))\n            }\n            return tryRecover(hash, v, r, s);\n        } else if (signature.length == 64) {\n            bytes32 r;\n            bytes32 vs;\n            // ecrecover takes the signature parameters, and the only way to get them\n            // currently is to use assembly.\n            assembly {\n                r := mload(add(signature, 0x20))\n                vs := mload(add(signature, 0x40))\n            }\n            return tryRecover(hash, r, vs);\n        } else {\n            return (address(0), RecoverError.InvalidSignatureLength);\n        }\n    }\n\n    /**\n     * @dev Returns the address that signed a hashed message (`hash`) with\n     * `signature`. This address can then be used for verification purposes.\n     *\n     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:\n     * this function rejects them by requiring the `s` value to be in the lower\n     * half order, and the `v` value to be either 27 or 28.\n     *\n     * IMPORTANT: `hash` _must_ be the result of a hash operation for the\n     * verification to be secure: it is possible to craft signatures that\n     * recover to arbitrary addresses for non-hashed data. A safe way to ensure\n     * this is by receiving a hash of the original message (which may otherwise\n     * be too long), and then calling {toEthSignedMessageHash} on it.\n     */\n    function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {\n        (address recovered, RecoverError error) = tryRecover(hash, signature);\n        _throwError(error);\n        return recovered;\n    }\n\n    /**\n     * @dev Overload of {ECDSA-tryRecover} that receives the `r` and `vs` short-signature fields separately.\n     *\n     * See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]\n     *\n     * _Available since v4.3._\n     */\n    function tryRecover(\n        bytes32 hash,\n        bytes32 r,\n        bytes32 vs\n    ) internal pure returns (address, RecoverError) {\n        bytes32 s = vs & bytes32(0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff);\n        uint8 v = uint8((uint256(vs) >> 255) + 27);\n        return tryRecover(hash, v, r, s);\n    }\n\n    /**\n     * @dev Overload of {ECDSA-recover} that receives the `r and `vs` short-signature fields separately.\n     *\n     * _Available since v4.2._\n     */\n    function recover(\n        bytes32 hash,\n        bytes32 r,\n        bytes32 vs\n    ) internal pure returns (address) {\n        (address recovered, RecoverError error) = tryRecover(hash, r, vs);\n        _throwError(error);\n        return recovered;\n    }\n\n    /**\n     * @dev Overload of {ECDSA-tryRecover} that receives the `v`,\n     * `r` and `s` signature fields separately.\n     *\n     * _Available since v4.3._\n     */\n    function tryRecover(\n        bytes32 hash,\n        uint8 v,\n        bytes32 r,\n        bytes32 s\n    ) internal pure returns (address, RecoverError) {\n        // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature\n        // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines\n        // the valid range for s in (301): 0 < s < secp256k1n ÷ 2 + 1, and for v in (302): v ∈ {27, 28}. Most\n        // signatures from current libraries generate a unique signature with an s-value in the lower half order.\n        //\n        // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value\n        // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or\n        // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept\n        // these malleable signatures as well.\n        if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {\n            return (address(0), RecoverError.InvalidSignatureS);\n        }\n        if (v != 27 && v != 28) {\n            return (address(0), RecoverError.InvalidSignatureV);\n        }\n\n        // If the signature is valid (and not malleable), return the signer address\n        address signer = ecrecover(hash, v, r, s);\n        if (signer == address(0)) {\n            return (address(0), RecoverError.InvalidSignature);\n        }\n\n        return (signer, RecoverError.NoError);\n    }\n\n    /**\n     * @dev Overload of {ECDSA-recover} that receives the `v`,\n     * `r` and `s` signature fields separately.\n     */\n    function recover(\n        bytes32 hash,\n        uint8 v,\n        bytes32 r,\n        bytes32 s\n    ) internal pure returns (address) {\n        (address recovered, RecoverError error) = tryRecover(hash, v, r, s);\n        _throwError(error);\n        return recovered;\n    }\n\n    /**\n     * @dev Returns an Ethereum Signed Message, created from a `hash`. This\n     * produces hash corresponding to the one signed with the\n     * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]\n     * JSON-RPC method as part of EIP-191.\n     *\n     * See {recover}.\n     */\n    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {\n        // 32 is the length in bytes of hash,\n        // enforced by the type signature above\n        return keccak256(abi.encodePacked(\"\\x19Ethereum Signed Message:\\n32\", hash));\n    }\n\n    /**\n     * @dev Returns an Ethereum Signed Message, created from `s`. This\n     * produces hash corresponding to the one signed with the\n     * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]\n     * JSON-RPC method as part of EIP-191.\n     *\n     * See {recover}.\n     */\n    function toEthSignedMessageHash(bytes memory s) internal pure returns (bytes32) {\n        return keccak256(abi.encodePacked(\"\\x19Ethereum Signed Message:\\n\", Strings.toString(s.length), s));\n    }\n\n    /**\n     * @dev Returns an Ethereum Signed Typed Data, created from a\n     * `domainSeparator` and a `structHash`. This produces hash corresponding\n     * to the one signed with the\n     * https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]\n     * JSON-RPC method as part of EIP-712.\n     *\n     * See {recover}.\n     */\n    function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32) {\n        return keccak256(abi.encodePacked(\"\\x19\\x01\", domainSeparator, structHash));\n    }\n}\n"
    },
    "@openzeppelin/contracts/token/ERC20/IERC20.sol": {
      "content": "// SPDX-License-Identifier: MIT\n// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC20/IERC20.sol)\n\npragma solidity ^0.8.0;\n\n/**\n * @dev Interface of the ERC20 standard as defined in the EIP.\n */\ninterface IERC20 {\n    /**\n     * @dev Returns the amount of tokens in existence.\n     */\n    function totalSupply() external view returns (uint256);\n\n    /**\n     * @dev Returns the amount of tokens owned by `account`.\n     */\n    function balanceOf(address account) external view returns (uint256);\n\n    /**\n     * @dev Moves `amount` tokens from the caller's account to `to`.\n     *\n     * Returns a boolean value indicating whether the operation succeeded.\n     *\n     * Emits a {Transfer} event.\n     */\n    function transfer(address to, uint256 amount) external returns (bool);\n\n    /**\n     * @dev Returns the remaining number of tokens that `spender` will be\n     * allowed to spend on behalf of `owner` through {transferFrom}. This is\n     * zero by default.\n     *\n     * This value changes when {approve} or {transferFrom} are called.\n     */\n    function allowance(address owner, address spender) external view returns (uint256);\n\n    /**\n     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.\n     *\n     * Returns a boolean value indicating whether the operation succeeded.\n     *\n     * IMPORTANT: Beware that changing an allowance with this method brings the risk\n     * that someone may use both the old and the new allowance by unfortunate\n     * transaction ordering. One possible solution to mitigate this race\n     * condition is to first reduce the spender's allowance to 0 and set the\n     * desired value afterwards:\n     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729\n     *\n     * Emits an {Approval} event.\n     */\n    function approve(address spender, uint256 amount) external returns (bool);\n\n    /**\n     * @dev Moves `amount` tokens from `from` to `to` using the\n     * allowance mechanism. `amount` is then deducted from the caller's\n     * allowance.\n     *\n     * Returns a boolean value indicating whether the operation succeeded.\n     *\n     * Emits a {Transfer} event.\n     */\n    function transferFrom(\n        address from,\n        address to,\n        uint256 amount\n    ) external returns (bool);\n\n    /**\n     * @dev Emitted when `value` tokens are moved from one account (`from`) to\n     * another (`to`).\n     *\n     * Note that `value` may be zero.\n     */\n    event Transfer(address indexed from, address indexed to, uint256 value);\n\n    /**\n     * @dev Emitted when the allowance of a `spender` for an `owner` is set by\n     * a call to {approve}. `value` is the new allowance.\n     */\n    event Approval(address indexed owner, address indexed spender, uint256 value);\n}\n"
    },
    "@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol": {
      "content": "// SPDX-License-Identifier: MIT\n// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)\n\npragma solidity ^0.8.0;\n\nimport \"../IERC20.sol\";\n\n/**\n * @dev Interface for the optional metadata functions from the ERC20 standard.\n *\n * _Available since v4.1._\n */\ninterface IERC20Metadata is IERC20 {\n    /**\n     * @dev Returns the name of the token.\n     */\n    function name() external view returns (string memory);\n\n    /**\n     * @dev Returns the symbol of the token.\n     */\n    function symbol() external view returns (string memory);\n\n    /**\n     * @dev Returns the decimals places of the token.\n     */\n    function decimals() external view returns (uint8);\n}\n"
    },
    "@openzeppelin/contracts/utils/Context.sol": {
      "content": "// SPDX-License-Identifier: MIT\n// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)\n\npragma solidity ^0.8.0;\n\n/**\n * @dev Provides information about the current execution context, including the\n * sender of the transaction and its data. While these are generally available\n * via msg.sender and msg.data, they should not be accessed in such a direct\n * manner, since when dealing with meta-transactions the account sending and\n * paying for execution may not be the actual sender (as far as an application\n * is concerned).\n *\n * This contract is only required for intermediate, library-like contracts.\n */\nabstract contract Context {\n    function _msgSender() internal view virtual returns (address) {\n        return msg.sender;\n    }\n\n    function _msgData() internal view virtual returns (bytes calldata) {\n        return msg.data;\n    }\n}\n"
    },
    "@openzeppelin/contracts/utils/Strings.sol": {
      "content": "// SPDX-License-Identifier: MIT\n// OpenZeppelin Contracts v4.4.1 (utils/Strings.sol)\n\npragma solidity ^0.8.0;\n\n/**\n * @dev String operations.\n */\nlibrary Strings {\n    bytes16 private constant _HEX_SYMBOLS = \"0123456789abcdef\";\n\n    /**\n     * @dev Converts a `uint256` to its ASCII `string` decimal representation.\n     */\n    function toString(uint256 value) internal pure returns (string memory) {\n        // Inspired by OraclizeAPI's implementation - MIT licence\n        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol\n\n        if (value == 0) {\n            return \"0\";\n        }\n        uint256 temp = value;\n        uint256 digits;\n        while (temp != 0) {\n            digits++;\n            temp /= 10;\n        }\n        bytes memory buffer = new bytes(digits);\n        while (value != 0) {\n            digits -= 1;\n            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));\n            value /= 10;\n        }\n        return string(buffer);\n    }\n\n    /**\n     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.\n     */\n    function toHexString(uint256 value) internal pure returns (string memory) {\n        if (value == 0) {\n            return \"0x00\";\n        }\n        uint256 temp = value;\n        uint256 length = 0;\n        while (temp != 0) {\n            length++;\n            temp >>= 8;\n        }\n        return toHexString(value, length);\n    }\n\n    /**\n     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.\n     */\n    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {\n        bytes memory buffer = new bytes(2 * length + 2);\n        buffer[0] = \"0\";\n        buffer[1] = \"x\";\n        for (uint256 i = 2 * length + 1; i > 1; --i) {\n            buffer[i] = _HEX_SYMBOLS[value & 0xf];\n            value >>= 4;\n        }\n        require(value == 0, \"Strings: hex length insufficient\");\n        return string(buffer);\n    }\n}\n"
    }
  },
  "settings": {
    "optimizer": {
      "enabled": true,
      "runs": 200
    },
    "outputSelection": {
      "*": {
        "*": [
          "abi",
          "evm.bytecode",
          "evm.deployedBytecode",
          "evm.methodIdentifiers",
          "metadata",