问题描述：6×9=42对于十进制来说是错误的，但是对于十三进制来说是正确的。即6（13）×9（13）=42（13），而42（13）=54（10）。你的任务是写一个程序读入3个整数p、q、r，然后确定一个进制B（2<=B<=16）使得p×q=r。如果B有很多选择，输出最小的一个。例如：p=11，q==11,r=121。则有11(3)×11(3)=121(3)，因为11(3)=4（10）和121(3)=16（10）。这种情况下，应该输出3。如果没有合适的进制，则输出0.

-Problem Descr iption: 6 × 9 = 42 for the metric system is wrong, but 13 M is correct. That is, 6 (13) × 9 (13) = 42 (13), while 42 (13) = 54 (10). Your task is to write a program to read three integers p, q, r, and then to identify a band B (2 <= B <= 16) makes p × q = r. If B have many choices, output the smallest one. For example: p = 11, q == 11, r = 121. There are 11 (3) × 11 (3) = 121 (3), because 11 (3) = 4 (10) and 121 (3) = 16 (10). Under the circumstances, should the output 3. If there are no suitable notation, then output 0.