#include<iostream>
#include<string>
#include<iomanip>
#include<cmath>
#include<vector>
#include<algorithm>
#include<utility>

using namespace std;

#define int long long
#define endl "\n"

constexpr long long INF = (long long)1e18;
constexpr long long MOD = 1'000'000'007; 

struct fast_io {
	fast_io(){
		std::cin.tie(nullptr);
		std::ios::sync_with_stdio(false);
	};
} fio;

signed main(){
	cout<<fixed<<setprecision(10);
	
	int T;
	vector<int> X(5'100'000);
	
	for(int i = 2; i < X.size(); i++){
		if(X[i] == true) continue;
		
		for(int j = i * i; j < X.size(); j += i){
			X[j] = true;
		}
	}
	
	cin>>T;
	
	for(int _ = 0; _ < T; _++){
		int A, P;
		
		cin>>A>>P;
		
		if(X[P] == true) cout<<-1<<endl;
		else cout<<1<<endl;
	}
	
	
	return 0;
}