#include <fstream>
using namespace std;
ifstream f("cmmdc.in");
ofstream g("cmmdc.out");
long long aux,a,b,r;
int main()
{
   f>>a>>b;
   if(a<b)
   {
    aux=b;
    b=a;
    a=aux;
   }
   r=a%b;
   while(r)
   {
     a=b;
     b=r;
     r=a%b;
   }
   if(b==1) b=0;
    g<<b<<'\n';
  return 0;
}