#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
const int MAX = 1e9;
const int MIN = -1*1e9;
const ll MAXLL = 1e18;
const ll MINLL = -1*1e18;

bool isPrime(ll N)
{
    if(N == 2) return true;
    for(int i = 2; i*i <= N; i++) {
        if(N%i==0) return false;
    }
    return true;
}

int main()
{
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int T; cin >> T;
    for(int t = 0; t < T; t++)
    {
        ll A,P; cin >> A >> P;
        cout << (isPrime(P) ? 1 : -1) << endl;
    }
    return 0;
}