module StrMap = Map.Make(String)

let solve alst =
  let rec solve' lst map =
    match lst with
    | [] -> map
    | x::xs ->
      let nextMap =
        if StrMap.mem x map then
          let cnt = StrMap.find x map in
          StrMap.add x (cnt + 1) map
        else
          StrMap.add x 1 map
      in
      solve' xs nextMap
  in
  solve' alst StrMap.empty |>
  StrMap.filter (fun k v -> v = 1) |>
  StrMap.cardinal

let () =
  let _ = read_line ()
  and alst = read_line () |>
             Str.split (Str.regexp_string " ")
  in
  solve alst |> print_int;
  print_newline ()