#include <fstream>

using namespace std;

int main()
{
    ifstream fin ("cmmdc.in");
    ofstream fout ("cmmdc.out");
    int a,b,y=1;
    fin>>a;fin>>b;
    if (b>a)
        {  while (y)
            { y=b%a;
              b=a;
              a=y;
        } if (b==1) fout<<0;
        else fout<<b;
        }
        else {
            while (y)
            {    y=a%b;
                 a=b;
                 b=y;
            } if (a==1) fout<<0;
            else fout<<a;
            }
    fout.close();
    return 0;
}