#include <iostream>
using namespace std;

int main()
{
    int T;
    long long N, K, r, ans;

    cin >> T;

    for (int i = 0; i < T; i++)
    {
        cin >> N;
        cin >> K;
        bool flag = false;
        long long j = N;
        if(N == K)
        {
            cout << -1 << "\n";
            continue;
        }
        while (j > 1)
        {
            long long k = 2;
            flag =  false;
            while (k <= K)
            {
                if (j % k == 0)
                {
                    r = j / k;

                    if (r <= K)
                    {
                        flag = true;
                        break;
                    }
                }

                k++;
            }
            if(flag == false)
            {
                cout << j << "\n";
                break;
            }
    
            j--;
        }
        if(flag == true){
            cout<<-1 << "\n";
        }
    }
    return 0;
}