#include <iostream>
#include <fstream>
#include <sstream>

using namespace std;

int cmmdc(int a,int b){
	while (a > 0 && b > 0){
		if (a > b){
			a = a - b;
		}
		else if(b > a){
			b = b - a;
		}
		else if (a == b && a == 1){
			return 0;
		}
		else{
			return a;
		}
	}
	return -1;
}


int main(){
	int a,b;
	string line;
	ifstream infile;
	ofstream outfile;

	infile.open("cmmdc.in");
	outfile.open("cmmdc.out");

	if (infile.is_open()){
		getline(infile,line);
		stringstream(line) >> a;

		getline(infile,line);
		stringstream(line) >> b;

		outfile << cmmdc(a,b);

		infile.close();
		outfile.close();
	}
	return 0;
}