import qualified Data.HashMap.Strict as HMS

type DataMap = HMS.HashMap String (String, String)

getDirection :: Char -> (a, a) -> a
getDirection 'L' = fst
getDirection 'R' = snd

countTimes :: String -> DataMap -> Int
countTimes directions m = countTimes' directions "AAA" 0
  where
    countTimes' (d:ds) s n
      | s == "ZZZ" = n
      | otherwise  = countTimes' ds (getDirection d $ m HMS.! s) (succ n)

getDataMap :: [String] -> DataMap
getDataMap = HMS.fromList . map parseLine
  where
    parseLine l = (take 3 l, (take 3 $ drop 7 l, take 3 $ drop 12 l))

main :: IO ()
main = do
  allLines <- lines <$> readFile "data.txt"
  let directions = cycle $ head allLines
      dataMap = getDataMap $ drop 2 allLines
  print $ countTimes directions dataMap