#include<bits/stdc++.h>
using namespace std;
#define ll long long
int main() {
   int T;
    cin >> T;
    
    while (T--) {
        ll n , k , x , y ;
        cin >> n >> k ;
        
        if (k >= n) {
            // We can increment all elements to at least 1
            x  = k - n;  // Remaining operations after making all elements >= 1
            y  = 1;      // The AND of all elements will be 1
            cout << x * y << endl;
        } 
        else {
            // We cannot make all elements >= 1, so Y will be 0
            cout << 0 << endl;
        }
    }
    
   
    
    return 0;
}