The three-digit number 133 is divisible by 3 after adding and subtracting an integer. What is the smallest integer?
三位数133与一个整数相加减后能被3整除，这个整数最小是多少．
<gadget id="calculator">1 + 3 + 3</gadget>
<output>7</output>

<gadget id="calculator">7 - 6</gadget>
<output>1</output>

<result>1</result>