#include <bits/stdc++.h>
using namespace std; 
using ll = long long;

bool is_prime(ll p){
    for(int i = 2; i * i <= p; i++){
        if(p % i == 0) return false;
    }
    return true;
}
int main(){
    int t; cin >> t;
    while(t--){
        ll a, p; cin >> a >> p;
        if(is_prime(p)){
            cout << 1 << endl;
        }
        else{
            cout << -1 << endl;
        }
    }
}