let read () = Scanf.scanf "%d " (fun i -> i)

let () =
  let n = read () in
  let a = Array.init n (fun _ -> read ()) in
  Array.fast_sort (-) a;
  let m =
    if n mod 2 = 1 then float a.(n / 2)
    else float (a.(n / 2) + a.(n / 2 - 1)) /. 2. in
  Printf.printf "%.1f\n" m