求数字的每个数位的和的问题，怎么利用C语言程序代码的程序编写步骤方式的实现

Question

Problem Description
Let S(N) be digit-sum of N, i.e S(109)=10,S(6)=6.

If two positive integers a,b are given, find the least positive integer n satisfying the condition a×S(n)=b×S(2n).

If there is no such number then output 0.

Input
The first line contains the number of test caces T(T≤10).
The next T lines contain two positive integers a,b(0<a,b<101).

Output
Output the answer in a new line for each test case.

Sample Input
3
2 1
4 1
3 4

Sample Output
1
0
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