GIven two positive integers N and K. You have to find the Kth smallest factor of N. A factor of N is a positive integer which divides N. Output the Kth smallest factor of N if it exists otherwise print -1.

Example 1:
Input : N = 4 , K = 2
Output: 2
Explanation:
All factors of 4 are 1,2 and 4. Out of
these 2 is the 2nd smallest.
Example 2:
Input : N = 4 , K = 3
Output: 4
Explanation:
All factors of 4 are 1,2 and 4. Out of
these 4 is the 3rd smallest.

Your Task:
You don't need to read input or print anything. Your task is to complete the function kThSmallestFactor() which takes 2 Integers N and K as input and returns the answer.

Expected Time Complexity: O(sqrt(N))
Expected Auxiliary Space: O(1)

Constraints:
1 <= N <= 10^{6}
1 <= K <= 10^{6}

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