#include <bits/stdc++.h>

using namespace std;
using ll = long long;

vector<bool> prime;

//O(NloglogN)
void erat(ll N){
    prime.resize(N+1, 1);
    prime[0] = 0;
    prime[1] = 0;
    for (ll i=2; i*i<=N; i++){
        if (prime[i]){
            for (ll j=i*2; j <= N; j+=i){
                prime[j] = 0;
            }
        }
    }
}

int main(){
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);

    erat(5000000);

    ll T, A, N;
    cin >> T;
    while(T){
        T--;
        cin >> A >> N;
        cout << (prime[N] ? 1 : -1) << '\n';
    }

    return 0;
}