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)
    |> Enum.reduce(1, fn x, acc -> acc * 2 + x end)
    |> IO.puts()
  end
end