module IO = struct (* @since 4.04.0 *) let split_on_char sep s = let open String in let r = ref [] in let j = ref (length s) in for i = length s - 1 downto 0 do if get s i = sep then begin r := sub s (i + 1) (!j - i - 1) :: !r; j := i end done; sub s 0 !j :: !r let read_ss () = read_line () |> split_on_char ' ' let read_ns () = read_ss () |> List.map int_of_string end let () = read_int () |> ignore; let a = IO.read_ns () in let a = List.fast_sort (-) a in let rec doit x p acc = function | [] -> if p then acc else x :: acc | a :: tl -> if x = a then doit x true acc tl else doit a false (if p then acc else x :: acc) tl in match a with | [] -> assert false | hd :: tl -> doit hd false [] tl |> List.length |> Printf.printf "%d\n"