let read_line () =
  try
    Some (read_line ())
  with End_of_file -> None

let strstr' p s n =
  try
    Some (Str.search_forward (Str.regexp_string p) s n)
  with Not_found -> None

let strstr p s = strstr' p s 0

let prefix s1 s2 = String.length s2 >= String.length s1 && Str.string_before s2 (String.length s1) = s1

let sanitize s =
  let rec san n acc =
    try
      let pos = Str.search_forward (Str.regexp "\\[\\|%\\|#") s n in
      let ender = match s.[pos] with
        | '[' -> ']'
        | _ -> s.[pos] in
      let pos' = String.index_from s (pos+1) ender in
      san (pos'+1) (acc ^ String.sub s n (pos-n))
    with Not_found -> acc ^ Str.string_after s n
  in san 0 ""

let rec initial () =
  match read_line () with
  | None -> ()
  | Some line ->
    match strstr "(**" line with
    | None -> initial ()
    | Some pos ->
      match strstr "*)" line with
      | None ->
        begin match strstr "[[" line with
          | None ->
            print_endline (sanitize (Str.string_after line (pos+3)));
            comment ()
          | Some _ -> runTo "]]"
        end
      | Some pos' ->
        let rest = Str.string_after line (pos+3) in
        if not (prefix " printing" rest || prefix " begin" rest || prefix " end" rest) then
          print_endline (sanitize (String.sub line (pos+3) (pos' - (pos+3))));
        initial ()

and comment () =
  match read_line () with
  | None -> ()
  | Some line ->
    match strstr "*)" line with
    | None ->
      begin match strstr "[[" line with
        | None ->
          begin match strstr "<<" line with
            | None ->
              print_endline (sanitize line);
              comment ()
            | Some _ -> runTo ">>"
          end
        | Some _ -> runTo "]]"
      end
    | Some pos ->
      print_endline (sanitize (Str.string_before line pos));
      initial ()

and runTo ender =
  match read_line () with
  | None -> ()
  | Some line ->
    match strstr ender line with
    | None -> runTo ender
    | _ ->
      match strstr "*)" line with
      | None -> comment ()
      | _ -> initial ()

let () = initial ()