let stream_fold f init st =
  let result = ref init in
  Stream.iter (fun x -> result := f !result x) st;
  !result

let stream_to_rev_list st =
  stream_fold (fun result elem -> elem :: result) [] st



let () =
  let st = Stream.from (fun i ->
    if i >= 3 then None
    else
      let c = (65 + i) |> char_of_int
      and h = read_line () |> int_of_string in
      Some(c, h)
  ) in
  st
  |> stream_to_rev_list
  |> List.sort (fun (c1, h1) (c2, h2) -> compare h2 h1)
  |> List.iter (fun (c, h) -> print_endline (String.make 1 c))