program euclid2;
var f,g:text;
    a,b,k:longint;
begin
assign(f,'euclid2.in');
assign(g,'euclid2.out');
reset(f);
rewrite(g);
read(f,a,b);
k:=a mod b;
while (k<>0)do
  begin
    a:=b;
    b:=k;
    k:=a mod b;
  end;
write(g,b);
close(f);
close(G);
end.