content: import Data.List (intersect)
  import Data.List.Split (splitOn)
  import qualified Data.Set as S
  
  main = do
      input <- map lines . splitOn "\n\n" <$> readFile "inputs/6.txt"
      print $ sum $ map (length . S.fromList . concat) input
      print $ sum $ map (length . intersectAll) input
  
  intersectAll :: Eq a => [[a]] -> [a]
  intersectAll = foldr1 intersect