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 Python (3.4.3) (judge verdict: Accepted)

# -*- coding: utf-8 -*-
# https://atcoder.jp/contests/abc120/tasks/abc120_b


def calc(a, b, k):
    ans = 0
    hit = 0
    for i in range(max(a, b), 0, -1):
        if a % i == 0 and b % i == 0:
            hit += 1
            if hit == k:
                ans = i
                break
    return ans


a, b, k = map(int, input().split())

print(calc(a, b, k))