program lab21;

var
  a, b, c: integer;

begin
  readln(a, b);

  if a < b then
  begin
    c := a;
    a := b;
    b := c;
  end;

  while b <> 0 do
  begin
    a := a mod b;
    c := a;
    a := b;
    b := c;
  end;

  writeln(a);
  readln;
end.