#include <stdio.h>
typedef long long ll;

int main(void)
{
  ll A, B, r, tmp;
  scanf("%lld %lld", &A, &B);

  if(A < B)
  {
    tmp = A;
    A = B;
    B = tmp;
  }

  r = A%B;
  while(r!=0)
  {
    A = B;
    B = r;
    r = A%B;
  }

  printf("%lld\n", B);

  return 0;
}