Problem:
Score : 200 points

Problem Statement

You are given positive integers A and B.

Find the K-th largest positive integer that divides both A and B.

The input guarantees that there exists such a number.

Constraints

All values in input are integers.

1 \leq A, B \leq 100

The K-th largest positive integer that divides both A and B exists.

K \geq 1

Input

Input is given from Standard Input in the following format:

A B K

Output

Print the K-th largest positive integer that divides both A and B.

Sample Input 1

8 12 2

Sample Output 1

2

Three positive integers divides both 8 and 12: 1, 2 and 4.
Among them, the second largest is 2.

Sample Input 2

100 50 4

Sample Output 2

5

Sample Input 3

1 1 1

Sample Output 3

1

Solution in Common Lisp (SBCL 1.1.14) (judge verdict: Accepted)

(let* ((a (read))
       (b (read))
       (c (read))
       (d (gcd a b))
       (lst nil))
  (loop :for n :from 1 :upto d :do (if (= 0 (mod a n) (mod b n))
                                       (push n lst)
                                       nil))
  (princ (nth (1- c) lst)))