contract ERC20 is IERC20 {
	using SafeMath for uint256;

	mapping (address => uint256) private _balances;

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

	uint256 private _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 balance of.
		* @return A 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 to 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) {
		_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) {
		_approve(msg.sender, spender, value);
		return true;
	}

	/**
	* @dev Transfer tokens from one address to another.
	* Note that while this function emits an Approval event, this is not required as per the specification,
		* and other compliant implementations may not emit the event.
		* @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) {
		_transfer(from, to, value);
		_approve(from, msg.sender, _allowed[from][msg.sender].sub(value));
		return true;
	}

	/**
	* @dev Increase the amount of tokens that an owner allowed to a spender.
	* approve should be called when _allowed[msg.sender][spender] == 0. To increment
	* allowed value is better to use this function to avoid 2 calls 
	*/
	function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
		_approve(msg.sender, spender, _allowed[msg.sender][spender].add(addedValue));
		return true;
	}

	/**
	* @dev Decrease the amount of tokens that an owner allowed to a spender.
	* approve should be called when _allowed[msg.sender][spender] == 0. To decrement
	* allowed value is better to use this function to avoid 2 calls (and wait until

	 */
	function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
		_approve(msg.sender, spender, _allowed[msg.sender][spender].sub(subtractedValue));
		return true;
	}

	/**
	* @dev Transfer token for a specified addresses
	* @param from The address to transfer from.
		* @param to The address to transfer to.
			* @param value The amount to be transferred.
			*/
	function _transfer(address from, address to, uint256 value) internal {
		require(to != address(0));

		_balances[from] = _balances[from].sub(value);
		_balances[to] = _balances[to].add(value);
		emit Transfer(from, to, value);
	}

	/**
	* @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 value The amount that will be created.
		*/
	function _mint(address account, uint256 value) internal {
		require(account != address(0));

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

	/**
	* @dev Internal function that burns an amount of the token of a given
	* account.
		* @param account The account whose tokens will be burnt.
		* @param value The amount that will be burnt.
		*/
	function _burn(address account, uint256 value) internal {
		require(account != address(0));

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

	/**
	* @dev Approve an address to spend another addresses' tokens.
	* @param owner The address that owns the tokens.
		* @param spender The address that will spend the tokens.
		* @param value The number of tokens that can be spent.
		*/
	function _approve(address owner, address spender, uint256 value) internal {
		require(spender != address(0));
		require(owner != address(0));

		_allowed[owner][spender] = value;
		emit Approval(owner, spender, value);
	}

	/**
	* @dev Internal function that burns an amount of the token of a given
	* account, deducting from the sender's allowance for said account. Uses the
	* internal burn function.
	* Emits an Approval event (reflecting the reduced allowance).
		* @param account The account whose tokens will be burnt.
		* @param value The amount that will be burnt.
		*/
	function _burnFrom(address account, uint256 value) internal {
		_burn(account, value);
		_approve(account, msg.sender, _allowed[account][msg.sender].sub(value));
	}
}
function _mint(address account, uint256 value) internal {
	require(account != address(0));

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

/**
 	* @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 value The amount that will be created.
 		*/