#include<bits/stdc++.h>
using namespace std;
using ll =long long;

void solve(){
    ll N,K;
    cin>>N>>K;
    if(K>=N){
        cout<<-1<<"\n";
        return;
    }
    while(N>K){
        bool eg=0;
        for(ll n=2;n*n<=N;n++){
            if(N%n==0){
                if(n<=K&&N/n<=K){
                    eg=1;
                    break;
                }
            }
        }
        if(!eg){
            cout<<N<<"\n";
            return;
        }
        N--;
    }
    cout<<-1<<"\n";
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int T;
    cin>>T;
    while(T--)solve();

}