let group_by cmp lst =
  let rec group_by' lst result =
    match lst with
    | [] -> result
    | x::xs ->
      let value = cmp x in
      let lst1, lst2 =
        List.partition (fun v -> value = cmp v) lst
      in
      group_by' lst2 ((value, lst1)::result)
  in
  group_by' lst []

let id x = x

let () =
  let _ = read_line () in
  let alst = read_line () |>
             Str.split (Str.regexp_string " ")
  in
  group_by id alst |>
  List.map (fun (key, vlst) -> List.length vlst) |>
  List.filter (( = ) 1) |>
  List.length |>
  print_int;
  print_newline ()