import qualified Data.ByteString.Lazy.Char8 as LC

branch :: Integral a => a -> Char -> a
branch n c = case c of
    'L' -> 2 * n
    'R' -> 2 * n + 1
    _ -> n

currentRoad :: Integral a => LC.ByteString -> a
currentRoad = LC.foldl' branch 1

main :: IO ()
main = print . currentRoad =<< LC.getContents