//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
using ll = long long;





void solve(){
    ll N, K; cin >> N >> K;
    for(ll i = N; i > K; --i){
        ll lim = (ll)sqrt(i);
        for(ll j = lim; j > 0; --j){
            if(i / j > K){
                cout << i << "\n";
                return;
            }
            if(i % j == 0){
                break;
            }
        }
    }
    cout << -1 << "\n";
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << setprecision(10) << fixed;

    int T;
    //T = 1;
    cin >> T;
    for(;T--;) solve();
}