contract ERC20 is ERC20Base {
    string public name;
    string public symbol;
    uint8 public decimals;

    constructor(string memory _name, string memory _symbol, uint8 _decimals, uint256 _total, address _fOwner) public {
        name = _name;
        symbol = _symbol;
        decimals = _decimals;
        _mint(_fOwner, _total);
    }


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


    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 value
    ); 

    /**
    * @dev Transfer token for a specified address
    * @param to The address to transfer to.
    * @param value The amount to be transferred.
    */

    function transfer(address to, uint256 value) public {
        _transfer(msg.sender, to, value);
    }

    /**
    * @dev Function to check the amount of tokens that an owner allowed to a spender.
    * @param owner address The address which owns the funds.
    * @param spender address The address which will spend the funds.
    * @return A uint256 specifying the amount of tokens still available for the spender.
    */
    
    function allowance(address owner, address spender) public view returns(uint) {
        return _allowed[owner][spender];
    }


    /**
    * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
    * Beware that changing an allowance with this method brings the risk that someone may use both the old
    * and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this
    * race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards:
    * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
    * @param spender The address which will spend the funds.
    * @param value The amount of tokens to be spent.
    */

    function approve(address spender, uint256 value) public {
        _checkRequireERC20(spender, value, true, _balanceOf[msg.sender]);

        _allowed[msg.sender][spender] = value;
        emit Approval(msg.sender, spender, value);
    }


    /**
    * @dev Transfer tokens from one address to another
    * @param from address The address which you want to send tokens from
    * @param to address The address which you want to transfer to
    * @param value uint256 the amount of tokens to be transferred
    */

    function transferFrom(address from, address to, uint256 value) public {
        _checkRequireERC20(to, value, true, _allowed[from][msg.sender]);

        _allowed[from][msg.sender] = SafeMath.sub(_allowed[from][msg.sender], value);
        _transfer(from, to, value);
    }

    /**
    * @dev Increase the amount of tokens that an owner allowed to a spender.
    * approve should be called when allowed_[_spender] == 0. To increment
    * allowed value is better to use this function to avoid 2 calls (and wait until
    * the first transaction is mined)
    * @param spender The address which will spend the funds.
    * @param value The amount of tokens to increase the allowance by.
    */

    function increaseAllowance(address spender, uint256 value)  public {
        _checkRequireERC20(spender, value, false, 0);
        require(_balanceOf[msg.sender] >= (_allowed[msg.sender][spender] + value), "Out of value");

        _allowed[msg.sender][spender] = SafeMath.add(_allowed[msg.sender][spender], value);
        emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
    }



    /**
    * @dev Decrease the amount of tokens that an owner allowed to a spender.
    * approve should be called when allowed_[_spender] == 0. To decrement
    * allowed value is better to use this function to avoid 2 calls (and wait until
    * the first transaction is mined)
    * @param spender The address which will spend the funds.
    * @param value The amount of tokens to decrease the allowance by.
    */

    function decreaseAllowance(address spender, uint256 value) public {
        _checkRequireERC20(spender, value, true, _allowed[msg.sender][spender]);

        _allowed[msg.sender][spender] = SafeMath.sub(_allowed[msg.sender][spender],value);
        emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
    }
}
function transferFrom(address from, address to, uint256 value) public {
    _checkRequireERC20(to, value, true, _allowed[from][msg.sender]);

    _allowed[from][msg.sender] = SafeMath.sub(_allowed[from][msg.sender], value);
    _transfer(from, to, value);
}

/**
 * @dev Transfer tokens from one address to another
 * @param from address The address which you want to send tokens from
 * @param to address The address which you want to transfer to
 * @param value uint256 the amount of tokens to be transferred
 */