#include<stdio.h>

typedef long long int ln;

void run(void){
  ln a,b;
  scanf("%lld%lld",&a,&b);

  ln r=a%b;
  while(r>0){
    a=b;
    b=r;
    r=a%b;
  }
  printf("%lld\n",b);
  return;
}

int main(void){
  run();
  return 0;
}