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 PYTHON3):

Solution:

from time import time


def num_factors(n):
    results = set()
    for i in range(1, int(n**(1/2)) + 1):
        if n % i == 0: results.update([i,int(n/i)])
    return results

n,k=map(int,input().split())
ttt=time()
t=num_factors(n)

if len(t) < k:
    print(-1)
else:
    tt=list(t)
    tt.sort()
    print(tt[k-1])