contract BurnableToken is StandardToken {
    event Burn(address indexed account, uint256 value);

    /**
     * @dev Burns a specific amount of tokens.
     * @param value The amount of token to be burned.
     */
    function burn(uint256 value) public {
        require(balances[msg.sender] >= value);
        totalSupply_ = totalSupply_.sub(value);
        balances[msg.sender] = balances[msg.sender].sub(value);
        emit Burn(msg.sender, value);
        emit Transfer(msg.sender, address(0), value);
    }

    /**
     * @dev Burns a specific amount of tokens which belong to appointed address of account.
     * @param account The address of appointed account.
     * @param value The amount of token to be burned.
     */
    function burnFrom(address account, uint256 value) public {
        require(account != address(0)); 
        require(balances[account] >= value);
        require(allowed[account][msg.sender] >= value);
        totalSupply_ = totalSupply_.sub(value);
        balances[account] = balances[account].sub(value);
        allowed[account][msg.sender] = allowed[account][msg.sender].sub(value);
        emit Burn(account, value);
        emit Transfer(account, address(0), value);
    }
}
function burnFrom(address account, uint256 value) public {
    require(account != address(0)); 
    require(balances[account] >= value);
    require(allowed[account][msg.sender] >= value);
    totalSupply_ = totalSupply_.sub(value);
    balances[account] = balances[account].sub(value);
    allowed[account][msg.sender] = allowed[account][msg.sender].sub(value);
    emit Burn(account, value);
    emit Transfer(account, address(0), value);
}

/**
 * @dev Burns a specific amount of tokens which belong to appointed address of account.
 * @param account The address of appointed account.
 * @param value The amount of token to be burned.
 */