#include <iostream>
#include <fstream>

using namespace std;

int gdc(int x, int y)
{
    if(x%y==0)
        return y;
    else
        return gdc(y, x%y);
}

int main()
{
    fstream inputFile, outputFile;
    inputFile.open("cmmdc.in", ios::in);
    outputFile.open("cmmdc.out", ios::out);

    int a, b, g;

    inputFile>>a>>b;

    if(b>a)
    {
        a=a+b;
        b=a-b;
        a=a-b;
    }

    g=gdc(a, b);

    if(g==1)
        outputFile<<0;
    else
        outputFile<<g;

    inputFile.close();
    outputFile.close();

    return 0;
}