let () =
  let rec charlist_of_string str n i =
    if i = n then [] else str.[i] :: charlist_of_string str n (i+1) in
  Scanf.scanf "%s\n" @@ fun s ->
  let lst = charlist_of_string s (String.length s) 0 in
  let ans =  List.fold_left (fun a x -> if x = 'L' then a*2 else a*2+1) 1 lst in
  Printf.printf "%d\n" ans