(* O(n) *)
open Hashtbl
let n = Scanf.scanf " %d" @@ (+) 0
let a_s = Array.init n @@ fun _ -> Scanf.scanf " %d" @@ (+) 0
let h = create n
let _ =
  Array.iter (fun a -> try ignore @@ find h a; remove h a with _ -> add h a 1) a_s;
  length h |> Printf.printf "%d\n"