contract GoCryptobotCoinERC20 {
    using SafeMath for uint256;

    string public constant name = "GoCryptobotCoin";
    string public constant symbol = "GCC";
    uint8 public constant decimals = 3;

    mapping(address => uint256) balances;
    mapping (address => mapping (address => uint256)) internal allowed;

    uint256 totalSupply_;

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

    /**
       @dev total number of tokens in existence
     */
    function totalSupply() public view returns (uint256) {
        return totalSupply_;
    }

    /**
       @dev Gets the balance of the specified address.
       @param _owner The address to query the the balance of.
       @return An uint256 representing the amount owned by the passed address.
     */
    function balanceOf(address _owner) public view returns (uint256 balance) {
        return balances[_owner];
    }

    /**
       @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 returns (bool) {
        require(_to != address(0));
        require(_value <= balances[msg.sender]);

        // SafeMath.sub will throw if there is not enough balance.
        balances[msg.sender] = balances[msg.sender].sub(_value);
        balances[_to] = balances[_to].add(_value);
        Transfer(msg.sender, _to, _value);
        return true;
    }

    /**
       @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 (uint256) {
        return allowed[_owner][_spender];
    }

    /**
       @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 returns (bool) {
        require(_to != address(0));
        require(_value <= balances[_from]);
        require(_value <= allowed[_from][msg.sender]);

        balances[_from] = balances[_from].sub(_value);
        balances[_to] = balances[_to].add(_value);
        allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
        Transfer(_from, _to, _value);
        return true;
    }

    /**
       @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 returns (bool) {
        allowed[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);
        return true;
    }

    /**
       @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)
       From MonolithDAO Token.sol
       @param _spender The address which will spend the funds.
       @param _addedValue The amount of tokens to increase the allowance by.
     */
    function increaseApproval(address _spender, uint _addedValue) public returns (bool) {
        allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
        Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
        return true;
    }

    /**
       @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)
       From MonolithDAO Token.sol
       @param _spender The address which will spend the funds.
       @param _subtractedValue The amount of tokens to decrease the allowance by.
     */
    function decreaseApproval(address _spender, uint _subtractedValue) public returns (bool) {
        uint oldValue = allowed[msg.sender][_spender];
        if (_subtractedValue > oldValue) {
            allowed[msg.sender][_spender] = 0;
        } else {
            allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
        }
        Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
        return true;
    }
}
function approve(address _spender, uint256 _value) public returns (bool) {
    allowed[msg.sender][_spender] = _value;
    Approval(msg.sender, _spender, _value);
    return true;
}

/**
 @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.
 */