#include <iostream>
#include <fstream>
using namespace std;

ifstream fin("cmmdc.in");
ofstream fout("cmmdc.out");

int main()
{
    int a, b;
    fin >> a;
    fin >> b;

    while (a != b) {
        if (a > b) {
            a = a - b;
        }
        else {
            b = b - a;
        }
    }
    if (a == 1 || b == 1) {
        fout << 0;
    }
    else {
        fout << a;
    }
}