defmodule Main do
  def main do
    IO.gets("")
    |> String.trim()
    |> String.to_charlist()
    |> Enum.map(fn x ->
      case to_string([x]) do
        "R" -> 1
        _ -> 0
      end
    end)
    |> solve
    |> IO.puts()
  end

  def solve(list) do
    if Enum.empty?(list) do
      1
    else
      {f, l} = List.pop_at(list, -1)
      solve(l) |> (&(&1 * 2 + f)).()
    end
  end
end