B

#include <bits/stdc++.h>

using namespace std;

#define _test   int _TEST; cin>>_TEST; while(_TEST--)

int main()
{
    _test
    {
        int a, b;
        cin>>a>>b;

        int x = 0, y = 0;

        while((b-x)>1 && (a+x)%(b-x) != 0)
            x++;
        while((a-y)>1 && (a-y)%(b+y) != 0)
            y++;

        if((a-y)%(b+y))     y = 1e9;

        cout<<min(x, y)<<"\n";
    }
}