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 Fortran (gfortran v4.8.4) (judge verdict: Accepted)

program k_th_common_divisor
  implicit none
  integer :: a, b, k, i, m = 0
  read(*,*) a, b, k
  do i = 100, 1, -1
    if (mod(a,i) == 0 .and. mod(b,i) == 0) m = m+1
    if (m == k) then
      write(*,'(i0)') i
      stop
    end if
  end do
end program k_th_common_divisor