#include <iostream>
#include <vector>
using namespace std;
using ll = long long int;
constexpr int TABLEMAX = 5000010;

int main(){
    vector<bool> isprime(TABLEMAX, true);
    isprime[0] = isprime[1] = false;
    for(int i = 2; i < TABLEMAX; i++){
        if(!isprime[i]) continue;
        for(int j = 2; i*j < TABLEMAX; j++) isprime[i*j] = false;
    }

    int t;
    cin >> t;
    while(t--){
        ll a, p;
        cin >> a >> p;
        if(!isprime[p]) cout << -1 << endl;
        else{
            cout << 1 << endl;
        }
    }
    return 0;
}