Problem: You are given two integers n and k. Find k-th smallest divisor of n, or report that it doesn't exist.

Divisor of n is any such natural number, that n can be divided by it without remainder.

Input

The first line contains two integers n and k (1 ≤ n ≤ 1015, 1 ≤ k ≤ 109).

Output

If n has less than k divisors, output -1.

Otherwise, output the k-th smallest divisor of n.

Examples

Input

4 2


Output

2


Input

5 3


Output

-1


Input

12 5


Output

6

Note

In the first example, number 4 has three divisors: 1, 2 and 4. The second one is 2.

In the second example, number 5 has only two divisors: 1 and 5. The third divisor doesn't exist, so the answer is -1.

Solution (in JAVA):

Solution:

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.StringTokenizer;

public class Edu_A {

	public static void main(String[] args) throws NumberFormatException, IOException {
		Scanner sc = new Scanner();
		long n = sc.nextLong();
		int k = sc.nextInt();

		long x = 1;
		ArrayList<Long> d = new ArrayList<Long>();
		while (x * x <= n) {
			if (n % x == 0) {
				d.add(x);
				if (x * x != n)
					d.add(n / x);
			}

			x++;
		}

		Collections.sort(d);
		if (d.size() < k)
			System.out.println(-1);
		else
			System.out.println(d.get(k - 1));

	}

	static class Scanner {
		BufferedReader br;
		StringTokenizer st;

		Scanner() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}

		Scanner(String file) throws FileNotFoundException {
			br = new BufferedReader(new FileReader(file));
		}

		String next() throws IOException {
			while (st == null || !st.hasMoreTokens())
				st = new StringTokenizer(br.readLine());
			return st.nextToken();
		}

		int nextInt() throws NumberFormatException, IOException {
			return Integer.parseInt(next());
		}

		String nextLine() throws IOException {
			return br.readLine();
		}

		long nextLong() throws NumberFormatException, IOException {
			return Long.parseLong(next());
		}

	}
}