#include<bits/stdc++.h>
using namespace std;
long long x,y;
int gcd(long long a,long long b){
	if(a==0){
		return b;
	} 
	else if(a<b) swap(a,b);
	else if(!(a & 1) && !(b & 1))return 2*gcd(a/2,b/2);
	else if(!(a & 1))return gcd(a/2,b);
	else if(!(b & 1))return gcd(a,b/2);
	else return gcd(a-b,b);
}
int main(){
	cin>>x>>y;
	cout<<gcd(x,y);  
	return 0;
}

如果x不是y的倍数or因数就会炸
rt求教