import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class KthSmallestFactor {
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int t = Integer.parseInt(br.readLine());
        long num;
        int k;
        for (int i = 0; i <= t; i++) {
            String[] l = br.readLine().split(" ");
            num = Long.parseLong(l[0]);
            k = Integer.parseInt(l[1]);
            System.out.println("result " + kthSmallest(num, k));
        }
    }

    public static long kthSmallest(long num, int k) {
        int incrementer = num % 2 == 0 ? 1 : 2;
        int count = 0;
        List<Long> list = new ArrayList<>();
        for (long i = 1; i <= Math.sqrt(num); i += incrementer) {
            if (num % i == 0) {
                count++;
                if (count == k) {
                    return i;
                }
                list.add(i);
                if (i != num / i) {
                    list.add((num / i));
                }
            }
        }
        Collections.sort(list);
        if (k - 1 < list.size()) {
            return list.get((int) (k - 1));
        }
        return -1;
    }
}