#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
using namespace std;
using ll = long long ;
using P = pair<int,int> ;
using pll = pair<long long,long long>;
constexpr int INF = 1e9;
constexpr long long LINF = 1e17;
constexpr int MOD = 1000000007;
constexpr double PI = 3.14159265358979323846;

void solve(){
    ll a,p;
    scanf("%lld %lld",&a,&p);
    for(int i=2;i*i<=p;i++){
        if(p%i==0){printf("%d\n",-1);return;}
    }
    printf("%d\n",1);
}

int main(){
    int t;
    scanf("%d",&t);
    while(t--){
        solve();
    }
    return 0;
}