A. Divisibility Problem.cpp

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n;
    cin>>n;
    for(int i=0;i<n;i++)
        {
   int a,b;

   cin>>a>>b;

    if(a%b==0)
    {
        cout<<"0"<<endl;
    }
    else
    {
        cout<<b-(a%b)<<endl;
    }
    }
}