Using 1, 2, and 4 can form 6 three-digit numbers without repeated numbers. What is the difference between the two numbers with the smallest difference among these three-digit numbers?
用1、2、4可以组成6个没有重复数字的三位数，这些三位数中相差最小的两个数之差是多少？
<gadget id="calculator">421 - 412</gadget>
<output>9</output>

<result>9</result>