#include <bits/stdc++.h>

/**
 * @title Sieve of Eratosthenes
 * @docs eratosthenes_sieve.md
 */
template <int MAX>
struct EratosthenesSieve{
  static std::bitset<MAX+1> is_prime;
  
  static void init(){
    is_prime.flip();
    is_prime[0] = is_prime[1] = false;
    
    for(int i = 2; i <= MAX; ++i){
      if(is_prime[i]){
        for(int j = 2*i; j <= MAX; j += i){
          is_prime[j] = false;
        }
      }
    }
  }
};

template <int MAX> std::bitset<MAX+1> EratosthenesSieve<MAX>::is_prime;


using E = EratosthenesSieve<5000000>;

int main(){
  E::init();
  
  std::cin.tie(0);
  std::ios::sync_with_stdio(false);
  
  int T; std::cin >> T;

  while(T--){
    int64_t A, P; std::cin >> A >> P;

    if(E::is_prime[P]){
      std::cout << 1 << "\n";
    }else{
      std::cout << -1 << "\n";
    }
  }
  

  return 0;
}