contract ERC20 is IERC20 {
	using SafeMath for uint256;




	mapping (address => uint256) internal balances_;




	mapping (address => mapping (address => uint256)) internal allowed_;




	uint256 internal totalSupply_;




	/**
	* @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) {
		return balances_[_owner];
	}




	/**
	* @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 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(_value <= balances_[msg.sender]);
		require(_to != address(0));




		balances_[msg.sender] = balances_[msg.sender].sub(_value);
		balances_[_to] = balances_[_to].add(_value);
		emit Transfer(msg.sender, _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;
		emit Approval(msg.sender, _spender, _value);
		return true;
	}




	/**
	* @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(_value <= balances_[_from]);
		require(_value <= allowed_[_from][msg.sender]);
		require(_to != address(0));




		balances_[_from] = balances_[_from].sub(_value);
		balances_[_to] = balances_[_to].add(_value);
		allowed_[_from][msg.sender] = allowed_[_from][msg.sender].sub(_value);
		emit Transfer(_from, _to, _value);
		return true;
	}




	/**
	* @dev Internal function that mints an amount of the token and assigns it to
	* an account. This encapsulates the modification of balances such that the
	* proper events are emitted.
	* @param _account The account that will receive the created tokens.
	* @param _amount The amount that will be created.
	*/
	function _mint(address _account, uint256 _amount) internal {
		require(_account != 0);
		totalSupply_ = totalSupply_.add(_amount);
		balances_[_account] = balances_[_account].add(_amount);
		emit Transfer(address(0), _account, _amount);
	}
}
/**
 * @title Standard ERC20 token
 *
 * @dev Implementation of the basic standard token.
 * https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md
 * Originally based on code by FirstBlood: https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
 */
function allowance(
	address _owner,
	address _spender
 )
	public
	view
	returns (uint256)
{
	return allowed_[_owner][_spender];
}

/**
 	* @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.
 	*/