#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define dl double
#define st first
#define nd second
#define II pair <int, int>

using namespace std;

const int N = 5 + 1e5;
const int inf = 7 + 1e9;

void solve() {
    int n, k;
    cin >> n >> k;
    if (n == k) {
        cout << "-1\n";
        return;
    }
    ll spr = (ll)k * k;
    if (spr < n) {
        cout << n << '\n';
        return;
    }
    while (n > 0) {
        int ok = 1;
        for (int i = 1; i * i <= n, i <= k; i ++)
            if (n % i == 0) {
                int x = n / i;
                if (x <= k) {
                    ok = 0;
                    break;
                }
            }
        if (ok) {
            cout << n << '\n';
            return;
        }
        n --;
    }
    cout << "-1\n";
}

int main() {
#define TASKNAME ""
    ios_base :: sync_with_stdio (0);
    cin.tie (0);
    if ( fopen( TASKNAME ".inp", "r" ) ) {
        freopen (TASKNAME ".inp", "r", stdin);
        freopen (TASKNAME ".out", "w", stdout);
    }
    int t;
    cin >> t;
    while (t --)
        solve();
    return 0;
}