#include <bits/stdc++.h>

using namespace std;

#define REP(i,n) for(int i=0; i<(int)(n); i++)

template <size_t N>
void psieve(bool (&p)[N]) {
  for (int i = 0; i < N; i++)
    p[i] = true;
  p[0] = p[1] = false;
  for (int i = 2; i * i < N; i++) {
    if (!p[i])
      continue;
    for (int j = i * i; j < N; j += i)
      p[j] = false;
  }
}

bool prime[5000000+1];

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  psieve(prime);

  int T;
  cin >> T;
  REP (i, T) {
    long long A;
    int P;
    cin >> A >> P;
    cout << (prime[A] ? 1 : -1) << endl;
  }
  
  return 0;
}