program cmmdc;

var a,b,r:longint;

procedure citire;
begin
assign(input,'euclid2.in');
reset(input);
read(a,b);
close(input);
end;

procedure cmmdc;
var w,q:longint;
begin
w:=a;
q:=b;
repeat
       r:=w mod q;
       w:=q;
       q:=r;
       until q=0;
if (w=1) and (a<>1) and (b<>1) then
   write(0)
   else write(w);
end;

begin
citire;
assign(output,'euclid2.out');
rewrite(output);
cmmdc;
close(output);
end.