var
  n,i:integer;
begin
  readln(n);
  while n mod 2=0 do n:=n div 2;
  for i:=2 to n-1 do if n mod (i+1)=0 then break;
  writeln(i);
end.

> var
>   n,i:integer;
> begin
>   readln(n);
>   while n mod 2=0 do n:=n div 2;
>   for i:=2 to n-1 do if n mod (i+1)=0 then break;
>   writeln(i);
> end.