#include <stdio.h>

int main(void)
{
	unsigned long long A,B,surplus = 1,left,right,most_anser;
	scanf("%llu %llu",&A,&B);
//				printf("%llu %llu\n",A, B);

	if(A+B < A*B){
		right = A+B;
		left = B;
	}else{
		right = B;
		left = A+B;
	}
	//		printf("%llu %llu\n",left, right);
	while(surplus != 0){
		surplus = left % right;
		//最大公約数を保存
		most_anser = right;
		left = right;
		right = surplus;
	//		printf("%llu %llu\n",left, right);

	}
	
	printf("%llu",most_anser);
	return 0;
}