#include <bits/stdc++.h>
using namespace std;
const int MX = 2200000;
int main() {
  vector<int> prime(MX , 0);
  for (int i = 2; i < MX; i++) {
    for (int j = i; j < MX; j += i) {
      prime[j]++;
    }
  }
  int t;
  cin >> t;
  while (t--) {
    long long a;
    int p;
    cin >> a >> p;
    if (prime[p] > 1) {
      cout << -1 << endl;
    } else {
      cout << 1 << endl;
    }
  }
  return 0;
}