// Sources flattened with hardhat v2.2.0 https://hardhat.org

// File openzeppelin-solidity/contracts/utils/introspection/IERC165.sol@v4.0.0

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}


// File openzeppelin-solidity/contracts/token/ERC721/IERC721.sol@v4.0.0



pragma solidity ^0.8.0;

/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721 is IERC165 {
    /**
     * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
     */
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
     */
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
     */
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    /**
     * @dev Returns the number of tokens in ``owner``'s account.
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    /**
     * @dev Returns the owner of the `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function ownerOf(uint256 tokenId) external view returns (address owner);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(address from, address to, uint256 tokenId) external;

    /**
     * @dev Transfers `tokenId` token from `from` to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 tokenId) external;

    /**
     * @dev Gives permission to `to` to transfer `tokenId` token to another account.
     * The approval is cleared when the token is transferred.
     *
     * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
     *
     * Requirements:
     *
     * - The caller must own the token or be an approved operator.
     * - `tokenId` must exist.
     *
     * Emits an {Approval} event.
     */
    function approve(address to, uint256 tokenId) external;

    /**
     * @dev Returns the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

    /**
     * @dev Approve or remove `operator` as an operator for the caller.
     * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
     *
     * Requirements:
     *
     * - The `operator` cannot be the caller.
     *
     * Emits an {ApprovalForAll} event.
     */
    function setApprovalForAll(address operator, bool _approved) external;

    /**
     * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
     *
     * See {setApprovalForAll}
     */
    function isApprovedForAll(address owner, address operator) external view returns (bool);

    /**
      * @dev Safely transfers `tokenId` token from `from` to `to`.
      *
      * Requirements:
      *
      * - `from` cannot be the zero address.
      * - `to` cannot be the zero address.
      * - `tokenId` token must exist and be owned by `from`.
      * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
      * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
      *
      * Emits a {Transfer} event.
      */
    function safeTransferFrom(address from, address to, uint256 tokenId, bytes calldata data) external;
}


// File openzeppelin-solidity/contracts/token/ERC721/IERC721Receiver.sol@v4.0.0



pragma solidity ^0.8.0;

/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
interface IERC721Receiver {
    /**
     * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
     * by `operator` from `from`, this function is called.
     *
     * It must return its Solidity selector to confirm the token transfer.
     * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
     *
     * The selector can be obtained in Solidity with `IERC721.onERC721Received.selector`.
     */
    function onERC721Received(address operator, address from, uint256 tokenId, bytes calldata data) external returns (bytes4);
}


// File openzeppelin-solidity/contracts/token/ERC721/extensions/IERC721Metadata.sol@v4.0.0



pragma solidity ^0.8.0;

/**
 * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Metadata is IERC721 {

    /**
     * @dev Returns the token collection name.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the token collection symbol.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
     */
    function tokenURI(uint256 tokenId) external view returns (string memory);
}


// File openzeppelin-solidity/contracts/token/ERC721/extensions/IERC721Enumerable.sol@v4.0.0



pragma solidity ^0.8.0;

/**
 * @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Enumerable is IERC721 {

    /**
     * @dev Returns the total amount of tokens stored by the contract.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns a token ID owned by `owner` at a given `index` of its token list.
     * Use along with {balanceOf} to enumerate all of ``owner``'s tokens.
     */
    function tokenOfOwnerByIndex(address owner, uint256 index) external view returns (uint256 tokenId);

    /**
     * @dev Returns a token ID at a given `index` of all the tokens stored by the contract.
     * Use along with {totalSupply} to enumerate all tokens.
     */
    function tokenByIndex(uint256 index) external view returns (uint256);
}


// File openzeppelin-solidity/contracts/utils/Address.sol@v4.0.0



pragma solidity ^0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}


// File openzeppelin-solidity/contracts/utils/Context.sol@v4.0.0



pragma solidity ^0.8.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}


// File openzeppelin-solidity/contracts/utils/Strings.sol@v4.0.0



pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant alphabet = "0123456789abcdef";

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0x00";
        }
        uint256 temp = value;
        uint256 length = 0;
        while (temp != 0) {
            length++;
            temp >>= 8;
        }
        return toHexString(value, length);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = alphabet[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }

}


// File openzeppelin-solidity/contracts/utils/introspection/ERC165.sol@v4.0.0



pragma solidity ^0.8.0;

/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165 is IERC165 {
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165).interfaceId;
    }
}


// File openzeppelin-solidity/contracts/token/ERC721/ERC721.sol@v4.0.0



pragma solidity ^0.8.0;








/**
 * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
 * the Metadata extension, but not including the Enumerable extension, which is available separately as
 * {ERC721Enumerable}.
 */
contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
    using Address for address;
    using Strings for uint256;

    // Token name
    string private _name;

    // Token symbol
    string private _symbol;

    // Mapping from token ID to owner address
    mapping (uint256 => address) private _owners;

    // Mapping owner address to token count
    mapping (address => uint256) private _balances;

    // Mapping from token ID to approved address
    mapping (uint256 => address) private _tokenApprovals;

    // Mapping from owner to operator approvals
    mapping (address => mapping (address => bool)) private _operatorApprovals;

    /**
     * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.
     */
    constructor (string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
        return interfaceId == type(IERC721).interfaceId
            || interfaceId == type(IERC721Metadata).interfaceId
            || super.supportsInterface(interfaceId);
    }

    /**
     * @dev See {IERC721-balanceOf}.
     */
    function balanceOf(address owner) public view virtual override returns (uint256) {
        require(owner != address(0), "ERC721: balance query for the zero address");
        return _balances[owner];
    }

    /**
     * @dev See {IERC721-ownerOf}.
     */
    function ownerOf(uint256 tokenId) public view virtual override returns (address) {
        address owner = _owners[tokenId];
        require(owner != address(0), "ERC721: owner query for nonexistent token");
        return owner;
    }

    /**
     * @dev See {IERC721Metadata-name}.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev See {IERC721Metadata-symbol}.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev See {IERC721Metadata-tokenURI}.
     */
    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
        require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");

        string memory baseURI = _baseURI();
        return bytes(baseURI).length > 0
            ? string(abi.encodePacked(baseURI, tokenId.toString()))
            : '';
    }

    /**
     * @dev Base URI for computing {tokenURI}. Empty by default, can be overriden
     * in child contracts.
     */
    function _baseURI() internal view virtual returns (string memory) {
        return "";
    }

    /**
     * @dev See {IERC721-approve}.
     */
    function approve(address to, uint256 tokenId) public virtual override {
        address owner = ERC721.ownerOf(tokenId);
        require(to != owner, "ERC721: approval to current owner");

        require(_msgSender() == owner || ERC721.isApprovedForAll(owner, _msgSender()),
            "ERC721: approve caller is not owner nor approved for all"
        );

        _approve(to, tokenId);
    }

    /**
     * @dev See {IERC721-getApproved}.
     */
    function getApproved(uint256 tokenId) public view virtual override returns (address) {
        require(_exists(tokenId), "ERC721: approved query for nonexistent token");

        return _tokenApprovals[tokenId];
    }

    /**
     * @dev See {IERC721-setApprovalForAll}.
     */
    function setApprovalForAll(address operator, bool approved) public virtual override {
        require(operator != _msgSender(), "ERC721: approve to caller");

        _operatorApprovals[_msgSender()][operator] = approved;
        emit ApprovalForAll(_msgSender(), operator, approved);
    }

    /**
     * @dev See {IERC721-isApprovedForAll}.
     */
    function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
        return _operatorApprovals[owner][operator];
    }

    /**
     * @dev See {IERC721-transferFrom}.
     */
    function transferFrom(address from, address to, uint256 tokenId) public virtual override {
        //solhint-disable-next-line max-line-length
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");

        _transfer(from, to, tokenId);
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(address from, address to, uint256 tokenId) public virtual override {
        safeTransferFrom(from, to, tokenId, "");
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory _data) public virtual override {
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
        _safeTransfer(from, to, tokenId, _data);
    }

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * `_data` is additional data, it has no specified format and it is sent in call to `to`.
     *
     * This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.
     * implement alternative mechanisms to perform token transfer, such as signature-based.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeTransfer(address from, address to, uint256 tokenId, bytes memory _data) internal virtual {
        _transfer(from, to, tokenId);
        require(_checkOnERC721Received(from, to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
    }

    /**
     * @dev Returns whether `tokenId` exists.
     *
     * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
     *
     * Tokens start existing when they are minted (`_mint`),
     * and stop existing when they are burned (`_burn`).
     */
    function _exists(uint256 tokenId) internal view virtual returns (bool) {
        return _owners[tokenId] != address(0);
    }

    /**
     * @dev Returns whether `spender` is allowed to manage `tokenId`.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {
        require(_exists(tokenId), "ERC721: operator query for nonexistent token");
        address owner = ERC721.ownerOf(tokenId);
        return (spender == owner || getApproved(tokenId) == spender || ERC721.isApprovedForAll(owner, spender));
    }

    /**
     * @dev Safely mints `tokenId` and transfers it to `to`.
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeMint(address to, uint256 tokenId) internal virtual {
        _safeMint(to, tokenId, "");
    }

    /**
     * @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is
     * forwarded in {IERC721Receiver-onERC721Received} to contract recipients.
     */
    function _safeMint(address to, uint256 tokenId, bytes memory _data) internal virtual {
        _mint(to, tokenId);
        require(_checkOnERC721Received(address(0), to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
    }

    /**
     * @dev Mints `tokenId` and transfers it to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - `to` cannot be the zero address.
     *
     * Emits a {Transfer} event.
     */
    function _mint(address to, uint256 tokenId) internal virtual {
        require(to != address(0), "ERC721: mint to the zero address");
        require(!_exists(tokenId), "ERC721: token already minted");

        _beforeTokenTransfer(address(0), to, tokenId);

        _balances[to] += 1;
        _owners[tokenId] = to;

        emit Transfer(address(0), to, tokenId);
    }

    /**
     * @dev Destroys `tokenId`.
     * The approval is cleared when the token is burned.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     *
     * Emits a {Transfer} event.
     */
    function _burn(uint256 tokenId) internal virtual {
        address owner = ERC721.ownerOf(tokenId);

        _beforeTokenTransfer(owner, address(0), tokenId);

        // Clear approvals
        _approve(address(0), tokenId);

        _balances[owner] -= 1;
        delete _owners[tokenId];

        emit Transfer(owner, address(0), tokenId);
    }

    /**
     * @dev Transfers `tokenId` from `from` to `to`.
     *  As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     *
     * Emits a {Transfer} event.
     */
    function _transfer(address from, address to, uint256 tokenId) internal virtual {
        require(ERC721.ownerOf(tokenId) == from, "ERC721: transfer of token that is not own");
        require(to != address(0), "ERC721: transfer to the zero address");

        _beforeTokenTransfer(from, to, tokenId);

        // Clear approvals from the previous owner
        _approve(address(0), tokenId);

        _balances[from] -= 1;
        _balances[to] += 1;
        _owners[tokenId] = to;

        emit Transfer(from, to, tokenId);
    }

    /**
     * @dev Approve `to` to operate on `tokenId`
     *
     * Emits a {Approval} event.
     */
    function _approve(address to, uint256 tokenId) internal virtual {
        _tokenApprovals[tokenId] = to;
        emit Approval(ERC721.ownerOf(tokenId), to, tokenId);
    }

    /**
     * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.
     * The call is not executed if the target address is not a contract.
     *
     * @param from address representing the previous owner of the given token ID
     * @param to target address that will receive the tokens
     * @param tokenId uint256 ID of the token to be transferred
     * @param _data bytes optional data to send along with the call
     * @return bool whether the call correctly returned the expected magic value
     */
    function _checkOnERC721Received(address from, address to, uint256 tokenId, bytes memory _data)
        private returns (bool)
    {
        if (to.isContract()) {
            try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, _data) returns (bytes4 retval) {
                return retval == IERC721Receiver(to).onERC721Received.selector;
            } catch (bytes memory reason) {
                if (reason.length == 0) {
                    revert("ERC721: transfer to non ERC721Receiver implementer");
                } else {
                    // solhint-disable-next-line no-inline-assembly
                    assembly {
                        revert(add(32, reason), mload(reason))
                    }
                }
            }
        } else {
            return true;
        }
    }

    /**
     * @dev Hook that is called before any token transfer. This includes minting
     * and burning.
     *
     * Calling conditions:
     *
     * - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
     * transferred to `to`.
     * - When `from` is zero, `tokenId` will be minted for `to`.
     * - When `to` is zero, ``from``'s `tokenId` will be burned.
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(address from, address to, uint256 tokenId) internal virtual { }
}


// File flatgreenearth/contracts/Acre.sol


	pragma solidity ^ 0.8.0;
	contract GreenPointLandReserves{
		address THIS = address(this);
		uint $ = 1e18;
		uint genesis;
		Totem public totemNFT;
		ERC20 MVT = ERC20(0x3D46454212c61ECb7b31248047Fa033120B88668);
		ERC20 MDT = ERC20(0x32A087D5fdF8c84eC32554c56727a7C81124544E);

		uint liquidityReserve;
		uint mvtRewardsPool;

		uint constant DAYS = 300;
		constructor(){
			genesis = block.timestamp;
			nextFloorRaisingTime = genesis + 86400 * 90;
			totemNFT = new Totem("Totem","TOTEM");
			GLR_nonprofit = 0xdeC30c12CfAfd3a1647a1a987A04b1b153bA3fBF;
			rolloutAmount = $ * 1000;// MVT / day
		}

		function shiftOwnership(address addr) public{
			require(msg.sender == GLR_nonprofit);
			GLR_nonprofit = addr;
		}

		function GLR_pullFunds() public{
			require(msg.sender == GLR_nonprofit && GLR_funds > 0);
			(bool success, ) = GLR_nonprofit.call{value:GLR_funds}("");
	        require(success, "Transfer failed.");
			GLR_funds = 0;
		}

	    function globalData() public view returns(uint _MVT_to_rollout, uint _mvt5xHodlPool, uint _nextFloorRaisingTime, uint _floorPrice, uint _totalACRESupply, uint _totalAcreWeight, uint _totalTotemWeight){
	    	return (MVT_to_rollout, mvt5xHodlPool, nextFloorRaisingTime, floorPrice, _totalSupply, totalShares[ETHpool], totalTotemWeight);
	    }
	    
	    function userData(address account) public view returns(uint acreBalance, uint totemWeight, uint acreDividends, uint totemDividends, bool MDT_approval, bool MVT_approval){
	    	return (balanceOf(account), shares[MVTpool][account] , dividendsOf(ETHpool, account), dividendsOf(MVTpool, account), MVT.allowance(account,THIS)>$*1000000, MDT.allowance(account,THIS)>$*1000000);
	    }

	    function userData2(address account) public view returns(uint MDT_balance, uint MVT_balance){
	    	return ( MDT.balanceOf(account), MVT.balanceOf(account) );
	    }

		address GLR_nonprofit;
		uint public GLR_funds;
		uint mvt5xHodlPool;
		event PurchaseAcre(address buyer, uint acreBought);
		function purchaseAcre() public payable{
			require(msg.value > 0);
			uint val = msg.value;
			mint(msg.sender, val);
			uint forBuyingMVT = val * (_totalSupply - totalTotemWeight) / _totalSupply;
			GLR_funds += val - forBuyingMVT;
			mvt5xHodlPool += forBuyingMVT;
			emit PurchaseAcre(msg.sender, val);
			rolloutDepositedMVTRewards();
		}


		uint nextFloorRaisingTime;
		uint floorPrice = $/20000;
		bool firstBump = true;
		function sell_MVT(uint amount) public{
			address payable sender = payable(msg.sender);
			MVT.transferFrom(sender, THIS, amount);
			uint NOW = block.timestamp;
			
			if(NOW >= nextFloorRaisingTime){
				if(firstBump){
					firstBump = false;
					floorPrice = floorPrice * 5;
				}else{
					floorPrice = floorPrice * 3;
				}
				nextFloorRaisingTime += 300 * 86400;
			}

			uint cost = floorPrice*amount/$;
			require( mvt5xHodlPool >= cost && cost > 0 );
			mvt5xHodlPool -= cost;

			require( totalShares[MVTpool] > 0 );
			earningsPer[MVTpool] += amount * scaleFactor / totalShares[MVTpool];

			(bool success, ) = sender.call{value:cost}("");
	        require(success, "Transfer failed.");
		}

		mapping(bool => mapping(address => uint)) shares;
		mapping(bool => uint) totalShares;
		mapping(bool => uint) earningsPer;
		mapping(bool => mapping(address => uint)) payouts;
		mapping(bool => mapping(address => uint)) earnings;
		uint256 constant scaleFactor = 0x10000000000000000;
		bool constant ETHpool = false;
		bool constant MVTpool = true;

	    function withdraw(bool pool) public{
	    	address payable sender = payable(msg.sender);
	    	update(pool, sender);

	    	uint earned = earnings[pool][sender];
	    	earnings[pool][sender] = 0;
	    	require(earned > 0);

	    	if(pool == ETHpool){
				(bool success, ) = sender.call{value:earned}("");
	        	require(success, "Transfer failed.");
	    	}else{
	    		MVT.transfer(sender, earned);
	    	}
	    }

		function addShares(bool pool, address account, uint amount) internal{
			update(pool, account);
			totalShares[pool] += amount;
			shares[pool][account] += amount;
		}

		function removeShares(bool pool, address account, uint amount) internal{
			update(pool, account);
			totalShares[pool] -= amount;
			shares[pool][account] -= amount;
		}

		function dividendsOf(bool pool, address account) public view returns(uint){
			uint owedPerShare = earningsPer[pool] - payouts[pool][account];
			return shares[pool][account] * owedPerShare / scaleFactor;
		}
		
		function update(bool pool, address account) internal {
			uint newMoney = dividendsOf(pool, account);
	        payouts[pool][account] = earningsPer[pool];
			earnings[pool][account] += newMoney;		
	    }

	    function payEthToAcreStakers() payable public{
	    	uint val = msg.value;
	    	require(totalShares[ETHpool]>0);
	    	earningsPer[ETHpool] += val * scaleFactor / totalShares[ETHpool];
	    }

	    uint rolloutAmount;
	    uint MVT_to_rollout;
	    uint lastRollout;

	    event DepositMVTForRewards(address addr, uint amount);
	    function depositMVTForRewards(uint amount) public{
	    	MVT.transferFrom(msg.sender, THIS, amount);
	    	MVT_to_rollout += amount;
	    	emit DepositMVTForRewards(msg.sender, amount);
	    }

	    event RolloutDepositedMVTRewards(uint amountToDistribute);
	    function rolloutDepositedMVTRewards() public{
	    	uint NOW = block.timestamp;
	    	if( (NOW - lastRollout) > 86400  && totalShares[MVTpool] > 0 &&  MVT_to_rollout > 0){
    			lastRollout = NOW;
    			uint amountToDistribute = MVT_to_rollout>rolloutAmount?rolloutAmount:MVT_to_rollout;
    			MVT_to_rollout -= amountToDistribute;
    			earningsPer[MVTpool] += amountToDistribute * scaleFactor / totalShares[MVTpool];
    			emit RolloutDepositedMVTRewards(amountToDistribute);
	    	}
	    }

	    string public name = "Acre";
	    string public symbol = "ACRE";
	    uint8 constant public decimals = 18;
		mapping(address => uint256) public balances;
		uint _totalSupply;

	    mapping(address => mapping(address => uint)) approvals;

		event Transfer(
			address indexed from,
			address indexed to,
			uint256 amount,
			bytes data
		);
		event Transfer(
			address indexed from,
			address indexed to,
			uint256 amount
		);
		
		event Mint(
			address indexed addr,
			uint256 amount
		);

		function mint(address _address, uint _value) internal{
			balances[_address] += _value;
			_totalSupply += _value;
			if(!isContract(_address)) addShares(ETHpool, _address, _value);
			emit Mint(_address, _value);
		}

		function totalSupply() public view returns (uint256) {
	        return _totalSupply;
	    }

	    function balanceOf(address _owner) public view returns (uint256 balance) {
			return balances[_owner];
		}

		function transfer(address _to, uint _value) public virtual returns (bool) {
			bytes memory empty;
			return transferToAddress(_to, _value, empty);
		}

		function transfer(address _to, uint _value, bytes memory _data) public virtual returns (bool) {
			if( isContract(_to) ){
				return transferToContract(_to, _value, _data);
			}else{
				return transferToAddress(_to, _value, _data);
			}
		}

		//function that is called when transaction target is an address
		function transferToAddress(address _to, uint _value, bytes memory _data) private returns (bool) {
			moveTokens(msg.sender, _to, _value);
			emit Transfer(msg.sender, _to, _value, _data);
			return true;
		}

		//function that is called when transaction target is a contract
		function transferToContract(address _to, uint _value, bytes memory _data) private returns (bool) {
			moveTokens(msg.sender, _to, _value);
			ERC223ReceivingContract receiver = ERC223ReceivingContract(_to);
			receiver.tokenFallback(msg.sender, _value, _data);
			emit Transfer(msg.sender, _to, _value, _data);
			return true;
		}

		function moveTokens(address _from, address _to, uint _amount) internal virtual{
			require( _amount <= balances[_from] );
			//update balances
			balances[_from] -= _amount;
			balances[_to] += _amount;

			if(!isContract(_from)) removeShares(ETHpool, _from, _amount);
			if(!isContract(_to)) addShares(ETHpool, _to, _amount);
	        emit Transfer(_from, _to, _amount);
		}

	    function allowance(address src, address guy) public view returns (uint) {
	        return approvals[src][guy];
	    }
	  	
	    function transferFrom(address src, address dst, uint amount) public returns (bool){
	        address sender = msg.sender;
	        require(approvals[src][sender] >=  amount);
	        require(balances[src] >= amount);
	        approvals[src][sender] -= amount;
	        moveTokens(src,dst,amount);
	        bytes memory empty;
	        emit Transfer(sender, dst, amount, empty);
	        return true;
	    }

	    event Approval(address indexed src, address indexed guy, uint amount);
	    function approve(address guy, uint amount) public returns (bool) {
	        address sender = msg.sender;
	        approvals[sender][guy] = amount;

	        emit Approval( sender, guy, amount );
	        return true;
	    }

	    function isContract(address _addr) public view returns (bool is_contract) {
			uint length;
			assembly {
				//retrieve the size of the code on target address, this needs assembly
				length := extcodesize(_addr)
			}
			if(length>0) {
				return true;
			}else {
				return false;
			}
		}

		uint NFTcount;
		
	    mapping(address => uint[]) public totemsHad;
	    mapping(address => mapping(uint => bool)) public alreadyHadAtleastOnce;

	    uint totalTotemWeight;
	    event AcreToTotem(address account, uint amount, bool autoStake);
		function acreToTotem(uint amount, bool autoStake) public returns(uint TOTEM_ID){
			address sender = msg.sender;
			MDT.transferFrom(sender, THIS, $);

			totemNFT.mintUniqueTokenTo(autoStake?THIS:sender, NFTcount, amount);
			if(autoStake){stakeNFT(sender,NFTcount);}else{
				totemsHad[sender].push(NFTcount);
				alreadyHadAtleastOnce[sender][NFTcount] == true;
			}

			NFTcount += 1;
			totalTotemWeight += amount;
			moveTokens(sender, THIS, amount);
	        bytes memory empty;
	        emit Transfer(sender, THIS, amount, empty);
	        emit AcreToTotem(sender, amount, autoStake);
	        return NFTcount - 1;
		}

		event TotemToMDT(address lastOwner, uint totemID);
		function totemToMDT(uint totemID) public{
			address sender = msg.sender;
			require(sender == staker[totemID]);
			MDT.transfer(sender, $);
			uint totemWeight = totemNFT.getWeight(totemID);
	        removeShares( MVTpool, sender, totemWeight );
	        staker[totemID] = address(0);

	        uint burnage = totemWeight * totalTotemWeight / _totalSupply;
        	moveTokens(THIS, sender, totemWeight - burnage);
        	_totalSupply -= burnage;
        	balances[THIS] -= burnage;

	        totalTotemWeight -= totemWeight;
	        
			emit TotemToMDT(sender, totemID);
		}

		mapping(uint => address) public staker;
		event StakeNFT(address who, uint tokenID);
		function stakeNFT(address who, uint256 tokenID) private{
			staker[tokenID] = who;

			if( !alreadyHadAtleastOnce[who][tokenID] ){
				totemsHad[who].push(tokenID);
				alreadyHadAtleastOnce[who][tokenID] == true;
			}

			addShares( MVTpool, who, totemNFT.getWeight(tokenID) );
			emit StakeNFT(who, tokenID);
		}

		event UnstakeNFT(address unstaker, uint tokenID);
		function unstakeNFT(uint tokenID) public{
			address sender = msg.sender;
			require(staker[tokenID] == sender);
	        removeShares( MVTpool, sender, totemNFT.getWeight(tokenID) );
	        staker[tokenID] = address(0);

	        totemNFT.transferFrom(THIS, sender, tokenID);
	        emit UnstakeNFT(sender, tokenID);
		}

		function viewTotems(address account) public view returns(uint[] memory tokenIDs, bool[] memory currentlyStaking, uint[] memory acreWeight, bool[] memory owned){
			uint L = totemsHad[account].length;

			tokenIDs = new uint[](L);
			acreWeight = new uint[](L);
			currentlyStaking = new bool[](L);
			owned = new bool[](L);

			uint tID;
			for(uint c = 0; c<L; c+=1){
				tID = totemsHad[account][c];
				tokenIDs[c] = tID;
				acreWeight[c] = totemNFT.getWeight(tID);
				currentlyStaking[c] = staker[tID] == account;
				owned[c] = ( staker[tID] == account || totemNFT.ownerOf(tID) == account );
			}
		}

		function onERC721Received(address from, uint256 tokenID, bytes memory _data) public returns(bytes4) {
			bytes4 empty;
			require( msg.sender == address(totemNFT) );
			stakeNFT(from, tokenID);
	        return empty;
	    }
	}

	abstract contract ERC20{
		function totalSupply() external virtual view returns (uint256);
	    function balanceOf(address account) external virtual view returns (uint256);
	    function allowance(address owner, address spender) external virtual view returns (uint256);
	    function transfer(address recipient, uint256 amount) external virtual returns (bool);
	    function approve(address spender, uint256 amount) external virtual returns (bool);
	    function transferFrom(address sender, address recipient, uint256 amount) external virtual returns (bool);
	}

	contract Totem is ERC721 {
	    constructor (string memory _name, string memory _symbol)
	        ERC721(_name, _symbol)
	    {
	    	greenpoint = msg.sender;
	    }

	    address greenpoint;
	    mapping(uint => uint)  weight;
	    function mintUniqueTokenTo(
	        address _to,
	        uint256 _tokenId,
	        uint _weight
	    ) public {
	    	require(msg.sender == greenpoint);
	        super._mint(_to, _tokenId);
	        weight[_tokenId] = _weight;
	    }

	    function getWeight(uint ID) public view returns(uint){
	    	return weight[ID];
	    }

	    function _baseURI() internal override pure returns (string memory) {
	        return "TOTEM:";
	    }
	}

	abstract contract ERC223ReceivingContract{
	    function tokenFallback(address _from, uint _value, bytes calldata _data) external virtual;
	}