#include <bits/stdc++.h>

#include <atcoder/fenwicktree.hpp>
#include <atcoder/segtree.hpp>
#include <atcoder/modint.hpp>
#include <atcoder/dsu.hpp>
#include <atcoder/lazysegtree.hpp>

using namespace atcoder;
using namespace std;
using ll = long long;
using ull = unsigned long long;
template <class T>
using max_heap = priority_queue<T>;
template <class T>
using min_heap = priority_queue<T, vector<T>, greater<>>;
ll ll_min = numeric_limits<ll>::min();
ll ll_max = numeric_limits<ll>::max();
ll ALPHABET_N = 26;
using mint = modint998244353;
#define rep(i, n) for (ll i = (ll)0; i < (ll)n; i++)
#define rep_(i, k, n) for (ll i = (ll)k; i < (ll)n; i++)
#define all(a) a.begin(), a.end()

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	ll t;
	cin >> t;
	rep(_, t)
	{
		ll n, k;
		cin >> n >> k;
		if (n <= k)
		{
			cout << -1 << endl;
			continue;
		}
		else if (k * k < n)
		{
			cout << n << endl;
			continue;
		}
		auto isBad = [&](ll x) -> bool
		{
			ll l = (x % k == 0 ? x / k : x / k + 1);
			ll root = sqrtl(x);
			ll cost1 = root;
			ll cost2 = (k >= l ? k - l + 1 : 0);
			if (cost1 < cost2)
			{
				for (ll t = 1; t <= root; t++)
				{
					if (x % t)
						continue;
					ll u = x / t;
					if (t <= k && u <= k)
						return true;
				}
				return false;
			}
			else
			{
				if (l > k)
					return false;
				for (ll a = l; a <= k; a++)
				{
					if (x % a == 0)
						return true;
				}
				return false;
			}
		};
		ll ans = -1;
		for (ll x = n; x > k; x--)
		{
			if (!isBad(x))
			{
				ans = x;
				break;
			}
		}
		cout << ans << endl;
	}
	return 0;
}