It is stipulated that a★b means among the divisors of b, the smallest one that cannot divide a evenly, for example: 6★20=4. If a positive integer m makes 21★m+20★m=8, what is the smallest possible value of m?
规定a★b表示在b的约数中，不能整除a的最小的那一个，例如：6★20=4．如果正整数m使得21★m+20★m=8，那么m的最小可能值是多少．
<gadget id="calculator">2 * 6</gadget>
<output>12</output>

<result>12</result>