#include <stdio.h>
#include <stdlib.h>

int cmmdc(int a, int b)
{
    int c;
    c=a%b;
    if(c%2!=0)
    {
        return 0;
    }
    else
    {while(a!=b)
    {
        if(a>b)
            a=a-b;
        else
            b=b-a;
    }

    }
    return a;
}

int main()
{
    FILE *f1,*f2;
    int a,b;
    f1=fopen("cmmdc.in","r");
    f2=fopen("cmmdc.out","w");
    fscanf(f1,"%d %d",&a,&b);
    fprintf(f2,"%d ",cmmdc(a,b));
}