with Ada.Text_IO, Ada.Integer_Text_IO, Ada.Float_Text_IO;
 use Ada.Text_IO, Ada.Integer_Text_IO, Ada.Float_Text_IO;

procedure main is
   N: Integer;
begin
   get(N);
   if (N rem 2 = 0) then
      put(0.5, 0, 6, 0);
   else
      put(Float(N / 2 + 1) / Float(N), 0, 6, 0);
   end if;
end main;
