/* -*- coding: utf-8 -*-
 *
 * 3253.cc:  No.3253 Banned Product - yukicoder
 */

#include<cstdio>
#include<algorithm>

using namespace std;

/* constant */

/* typedef */

using ll = long long;

/* global variables */

/* subroutines */

/* main */

int main() {
  int tn;
  scanf("%d", &tn);

  while (tn--) {
    int n, k;
    scanf("%d%d", &n, &k);

    if (n > (ll)k * k) { printf("%d\n", n); continue; }
    
    int minn = max(2, n - 281);
    for (; n >= minn; n--) {
      bool ok = true;
      for (int p = 1; p <= k && p * p <= n; p++)
	if (n % p == 0) {
	  int q = n / p;
	  if (q <= k) { ok = false; break; }
	}

      if (ok) break;
    }

    printf("%d\n", (n >= minn) ? n : -1);
  }

  return 0;
}