let solve s =
  let len_s = String.length s in

  let rec solve' idx result =
    if idx >= len_s then result
    else
      let next_result =
        match s.[idx] with
        | 'L' -> result * 2
        | 'R' -> result * 2 + 1
        | _ -> failwith "hoge"
      in
      solve' (idx + 1) next_result
  in
  solve' 0 1

let () =
  let s = read_line () in
  solve s |> string_of_int |> print_endline