#include <fstream.h>
#include <iostream.h>

ifstream fin("cmmdc.in");
ofstream fout("cmmdc.out");
long a,b,r;
int main(){
  fin>>a>>b;
  for (r=a%b; r>0; a=b,b=r,r=a%b){;}
  fout<<b<<endl;
}