let string_1_list_of_string x =
  String.to_seq x
  |> List.of_seq
  |> List.map (String.make 1);;

let line s =
  if (List.hd s) = "-" then begin print_int 0; print_newline (); end
  else if (List.length s) < 3 then begin print_int 0; print_newline (); end
  else
    begin
      List.rev s |> List.tl |> List.tl |> List.rev |> String.concat "" |>
      print_string; print_newline ();
    end;;

let () = read_line () |> string_1_list_of_string |> line;;