Divisibility Problem

给定正整数 $a,b$，求至少把 $a$ 加上多少才能让 $a$ 为 $b$ 的倍数。 多组数据，$T\le10^4$，$a,b\le10^9$。

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.

The first line of the input contains one integer $ t $ ( $ 1 \le t \le 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 \le a, b \le 10^9 $ ).

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

5
10 4
13 9
100 13
123 456
92 46

2
5
4
333
0