#include <iostream>
#include <fstream>

using namespace std;
ifstream fin("cmmdc.in");
ofstream fout("cmmdc.out");
int unsigned a, b, d;
   void euclid(int a, int b, int d)
{
    if (b == 0)
        d = a;
    else
        euclid(b, a % b, d);
}

int main()
{
    fin>>a;
    fin>>b;
    euclid(a, b, d);
    if(a!=1)
    {fout<<a;}
    else{fout<<'0';}
    fin.close();
    fout.close();
    return 0;
}