#pragma region
#pragma GCC target("avx2")
#pragma GCC optimize("03")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std; typedef long double ld; typedef long long ll;
typedef unsigned long long ull;
#define endl "\n"
#define FOR(i,a,b) for(int i=(a);i<=(b);i++)
#define rep(i,n) for(int i=0;i<(n);i++)
#define PII pair<int, int>
#define PLL pair<ll, ll>
#define ALL(x) (x).begin(), (x).end()
constexpr int INF=1<<30; constexpr ll LINF=1LL<<60; constexpr ll mod=1e9+7; constexpr int NIL = -1;
template<class T>inline bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T>inline bool chmin(T &a, const T &b) { if (b<a) { a = b; return 1; } return 0; }
#pragma endregion
//-------------------

const int MAX_N = 5000002;
vector<int> primes;
vector<bool> isPrime;
void seive(int n){
    isPrime.resize(n+1, true);
    isPrime[0] = isPrime[1] = false;
    for(int i=2; i<=n; i++){
        if(isPrime[i]){
            primes.push_back(i);
            for(int j=2*i; j<=n; j+=i) isPrime[j] = false;
        }
    }
}

int main(){
    cin.tie(0); ios::sync_with_stdio(false); //cout << fixed << setprecision(15);
    seive(MAX_N-1);
    int T; cin >> T;
    while(T--) {
        ll a,p; cin >> a >> p;

        if(isPrime[p]) cout << 1 << endl;
        else cout << -1 << endl;
    }
    return 0;
}