write a go solution for Description:
You are given two positive integers a and b. In one move you can increase a by 1 (replace a with a+1). Your task is to find the minimum number of moves you need to do in order to make a divisible by b. It is possible, that you have to make 0 moves, as a is already divisible by b. You have to answer t independent test cases.

Input Format:
The first line of the input contains one integer t (1<=t<=10^4) — the number of test cases. Then t test cases follow.

The only line of the test case contains two integers a and b (1<=a,b<=10^9).

Output Format:
For each test case print the answer — the minimum number of moves you need to do in order to make a divisible by b.

Note:
None. Output only the code with no comments, explanation, or additional text.