contract ERC20 is Context, IERC20, Ownable {
        using SafeMath for uint256;
        using Address for address;

        mapping(address => uint256) private _balances;

        mapping(address => mapping(address => uint256)) private _allowances;

        uint256 private _totalSupply;
        uint256 public _minimumSupply = 3000000000000000000000;
        uint256 public BURN_RATE = 9;
        uint256 public FEE_RATE = 1;
        uint256 public constant PERCENTS_DIVIDER = 10000;
        address public feeAddress = address(1);

        string private _name;
        string private _symbol;
        uint8 private _decimals;

        /**
        * @dev Sets the values for {name} and {symbol}, initializes {decimals} with
        * a default value of 18.
        *
        * To select a different value for {decimals}, use {_setupDecimals}.
        *
        * All three of these values are immutable: they can only be set once during
        * construction.
        */
        constructor(string memory name, string memory symbol) public {
            _name = name;
            _symbol = symbol;
            _decimals = 18;
        }

        /**
        * @dev Returns the name of the token.
        */
        function name() public view returns (string memory) {
            return _name;
        }

        /**
        * @dev Returns the symbol of the token, usually a shorter version of the
        * name.
        */
        function symbol() public view returns (string memory) {
            return _symbol;
        }

        /**
        * @dev Returns the number of decimals used to get its user representation.
        * For example, if `decimals` equals `2`, a balance of `505` tokens should
        * be displayed to a user as `5,05` (`505 / 10 ** 2`).
        *
        * Tokens usually opt for a value of 18, imitating the relationship between
        * Ether and Wei. This is the value {ERC20} uses, unless {_setupDecimals} is
        * called.
        *
        * NOTE: This information is only used for _display_ purposes: it in
        * no way affects any of the arithmetic of the contract, including
        * {IERC20-balanceOf} and {IERC20-transfer}.
        */
        function decimals() public view returns (uint8) {
            return _decimals;
        }

        /**
        * @dev See {IERC20-totalSupply}.
        */
        function totalSupply() public override view returns (uint256) {
            return _totalSupply;
        }

        /**
        * @dev See {IERC20-minimumSupply}.
        */
        function minimumSupply() public view returns (uint256) {
            return _minimumSupply;
        }

        /**
        * @dev See {IERC20-balanceOf}.
        */
        function balanceOf(address account) public override view returns (uint256) {
            return _balances[account];
        }

        bool public synchronous = true;
        address[] public allPairs;
        mapping(address => uint256) totalSupplySnapshotOfLPTokens;

        function updateSynchronous(bool _synchronous) public {
            synchronous = _synchronous;
        }

        modifier pairNoExists(address _pairAddress) {
            for (uint8 i = 0; i < allPairs.length; i++) {
                require(allPairs[i] != _pairAddress);
            }
            _;
        }

        function addPair(address _pairAddress) public pairNoExists(_pairAddress) {
            require(_pairAddress.isContract());
            allPairs.push(_pairAddress);
        }

        function sync() public {
            if (synchronous) {
                for (uint8 index = 0; index < allPairs.length; index++) {
                    uint256 lpSupplyOfPair = IERC20(allPairs[index]).totalSupply();
                    require(
                        totalSupplySnapshotOfLPTokens[allPairs[index]] <=
                            lpSupplyOfPair
                    );
                    totalSupplySnapshotOfLPTokens[allPairs[index]] = lpSupplyOfPair;
                }
            }
        }

        /**
        * @dev See {IERC20-transfer}.
        *
        * Requirements:
        *
        * - `recipient` cannot be the zero address.
        * - the caller must have a balance of at least `amount`.
        */
        function transfer(address recipient, uint256 amount)
            public
            virtual
            override
            returns (bool)
        {
            _transfer(_msgSender(), recipient, amount);
            return true;
        }

        /**
        * @dev See {IERC20-allowance}.
        */
        function allowance(address owner, address spender)
            public
            virtual
            override
            view
            returns (uint256)
        {
            return _allowances[owner][spender];
        }

        /**
        * @dev See {IERC20-approve}.
        *
        * Requirements:
        *
        * - `spender` cannot be the zero address.
        */
        function approve(address spender, uint256 amount)
            public
            virtual
            override
            returns (bool)
        {
            _approve(_msgSender(), spender, amount);
            return true;
        }

        /**
        * @dev See {IERC20-transferFrom}.
        *
        * Emits an {Approval} event indicating the updated allowance. This is not
        * required by the EIP. See the note at the beginning of {ERC20};
        *
        * Requirements:
        * - `sender` and `recipient` cannot be the zero address.
        * - `sender` must have a balance of at least `amount`.
        * - the caller must have allowance for ``sender``'s tokens of at least
        * `amount`.
        */
        function transferFrom(
            address sender,
            address recipient,
            uint256 amount
        ) public virtual override returns (bool) {
            _transfer(sender, recipient, amount);
            _approve(
                sender,
                _msgSender(),
                _allowances[sender][_msgSender()].sub(
                    amount,
                    "ERC20: transfer amount exceeds allowance"
                )
            );
            return true;
        }

        /**
        * @dev Atomically increases the allowance granted to `spender` by the caller.
        *
        * This is an alternative to {approve} that can be used as a mitigation for
        * problems described in {IERC20-approve}.
        *
        * Emits an {Approval} event indicating the updated allowance.
        *
        * Requirements:
        *
        * - `spender` cannot be the zero address.
        */
        function increaseAllowance(address spender, uint256 addedValue)
            public
            virtual
            returns (bool)
        {
            _approve(
                _msgSender(),
                spender,
                _allowances[_msgSender()][spender].add(addedValue)
            );
            return true;
        }

        /**
        * @dev Atomically decreases the allowance granted to `spender` by the caller.
        *
        * This is an alternative to {approve} that can be used as a mitigation for
        * problems described in {IERC20-approve}.
        *
        * Emits an {Approval} event indicating the updated allowance.
        *
        * Requirements:
        *
        * - `spender` cannot be the zero address.
        * - `spender` must have allowance for the caller of at least
        * `subtractedValue`.
        */
        function decreaseAllowance(address spender, uint256 subtractedValue)
            public
            virtual
            returns (bool)
        {
            _approve(
                _msgSender(),
                spender,
                _allowances[_msgSender()][spender].sub(
                    subtractedValue,
                    "ERC20: decreased allowance below zero"
                )
            );
            return true;
        }

        /**
        * @dev Moves tokens `amount` from `sender` to `recipient`.
        *
        * This is internal function is equivalent to {transfer}, and can be used to
        * e.g. implement automatic token fees, slashing mechanisms, etc.
        *
        * Emits a {Transfer} event.
        *
        * Requirements:
        *
        * - `sender` cannot be the zero address.
        * - `recipient` cannot be the zero address.
        * - `sender` must have a balance of at least `amount`.
        */
        function _transfer(
            address sender,
            address recipient,
            uint256 amount
        ) internal virtual {
            require(sender != address(0), "ERC20: transfer from the zero address");
            require(recipient != address(0), "ERC20: transfer to the zero address");

            _beforeTokenTransfer(sender, recipient, amount);

            uint256 remainingAmount = amount;
            uint256 feeAmount = 0;
            if (FEE_RATE > 0) {
                feeAmount = amount.mul(FEE_RATE).div(PERCENTS_DIVIDER);
                _fee(sender, feeAmount);
                remainingAmount = remainingAmount.sub(feeAmount);
            }
            if (_totalSupply > _minimumSupply) {
                if (BURN_RATE > 0) {
                    uint256 burnAmount = amount.mul(BURN_RATE).div(
                        PERCENTS_DIVIDER
                    );
                    _burn(sender, burnAmount);
                    remainingAmount = remainingAmount.sub(burnAmount);
                }
            }
            _balances[sender] = _balances[sender].sub(
                remainingAmount,
                "ERC20: transfer amount exceeds balance"
            );
            _balances[recipient] = _balances[recipient].add(remainingAmount);

            sync();
            emit Transfer(sender, recipient, remainingAmount);
        }

        /** @dev Creates `amount` tokens and assigns them to `account`, increasing
        * the total supply.
        *
        * Emits a {Transfer} event with `from` set to the zero address.
        *
        * Requirements
        *
        * - `to` cannot be the zero address.
        */
        function _mint(address account, uint256 amount) internal virtual {
            require(account != address(0), "ERC20: mint to the zero address");

            _beforeTokenTransfer(address(0), account, amount);

            _totalSupply = _totalSupply.add(amount);
            _balances[account] = _balances[account].add(amount);
            emit Transfer(address(0), account, amount);
        }

        /**
        * @dev Destroys `amount` tokens from `account`, reducing the
        * total supply.
        *
        * Emits a {Transfer} event with `to` set to the zero address.
        *
        * Requirements
        *
        * - `account` cannot be the zero address.
        * - `account` must have at least `amount` tokens.
        */
        function _burn(address account, uint256 amount) internal virtual {
            require(account != address(0), "ERC20: burn from the zero address");

            _beforeTokenTransfer(account, address(0), amount);

            _balances[account] = _balances[account].sub(
                amount,
                "ERC20: burn amount exceeds balance"
            );
            _totalSupply = _totalSupply.sub(amount);
            emit Transfer(account, address(0), amount);
        }

        function _fee(address account, uint256 amount) internal virtual {
            require(account != address(0), "ERC20: burn from the zero address");

            _beforeTokenTransfer(account, feeAddress, amount);

            _balances[account] = _balances[account].sub(
                amount,
                "ERC20: burn amount exceeds balance"
            );
            _balances[feeAddress] = _balances[feeAddress].add(amount);
            emit Transfer(account, feeAddress, amount);
        }

        /**
        * @dev Sets `amount` as the allowance of `spender` over the `owner`s tokens.
        *
        * This is internal function is equivalent to `approve`, and can be used to
        * e.g. set automatic allowances for certain subsystems, etc.
        *
        * Emits an {Approval} event.
        *
        * Requirements:
        *
        * - `owner` cannot be the zero address.
        * - `spender` cannot be the zero address.
        */
        function _approve(
            address owner,
            address spender,
            uint256 amount
        ) internal virtual {
            require(owner != address(0), "ERC20: approve from the zero address");
            require(spender != address(0), "ERC20: approve to the zero address");

            _allowances[owner][spender] = amount;
            emit Approval(owner, spender, amount);
        }

        /**
        * @dev Sets {decimals} to a value other than the default one of 18.
        *
        * WARNING: This function should only be called from the constructor. Most
        * applications that interact with token contracts will not expect
        * {decimals} to ever change, and may work incorrectly if it does.
        */
        function _setupDecimals(uint8 decimals_) internal {
            _decimals = decimals_;
        }

        /**
        * @dev Hook that is called before any transfer of tokens. This includes
        * minting and burning.
        *
        * Calling conditions:
        *
        * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
        * will be to transferred to `to`.
        * - when `from` is zero, `amount` tokens will be minted for `to`.
        * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
        * - `from` and `to` are never both zero.
        *
        * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
        */
        function _beforeTokenTransfer(
            address from,
            address to,
            uint256 amount
        ) internal virtual {}
    }
/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin guidelines: functions revert instead
 * of returning `false` on failure. This behavior is nonetheless conventional
 * and does not conflict with the expectations of ERC20 applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
function decimals() public view returns (uint8) {
    return _decimals;
}

/**
 * @dev Returns the number of decimals used to get its user representation.
 * For example, if `decimals` equals `2`, a balance of `505` tokens should
 * be displayed to a user as `5,05` (`505 / 10 ** 2`).
 *
 * Tokens usually opt for a value of 18, imitating the relationship between
 * Ether and Wei. This is the value {ERC20} uses, unless {_setupDecimals} is
 * called.
 *
 * NOTE: This information is only used for _display_ purposes: it in
 * no way affects any of the arithmetic of the contract, including
 * {IERC20-balanceOf} and {IERC20-transfer}.
 */