let () =
  Scanf.scanf "%d\n" @@ fun n ->
  let arr = Array.init n @@ fun _ -> Scanf.scanf "%f " @@ fun f -> f in
  let () = Array.fast_sort compare arr in
  let len = Array.length arr in
  Printf.printf "%.1f\n"
    (if len mod 2 = 0 then (arr.(len/2-1) +. arr.(len/2)) /. 2. else arr.(len/2))