import System.IO

type SpaceImage = String

type Size = (Int, Int)
totalSize size = fst size * snd size

count :: Eq a => a -> [a] -> Int
count x = length . filter (x==)

data Layer = Layer { getData :: [Int] } deriving (Show)

instance Eq Layer where
  (Layer a) == (Layer b) = count 0 a == count 0 b

instance Ord Layer where
  compare (Layer a) (Layer b) = count 0 a `compare` count 0 b

identifyLayer :: Layer -> Int
identifyLayer (Layer l) = count 1 l * count 2 l

layerFits :: Size -> SpaceImage -> Bool
layerFits size img = length img `div` totalSize size > 0

parseLayer :: Size -> SpaceImage -> Layer
parseLayer size img = Layer $ map (read . pure :: Char -> Int) $ take (totalSize size) img

parseLayers :: Size -> SpaceImage -> [Layer]
parseLayers size img
  | layerFits size img = do let layer = parseLayer size img
                            [layer] ++ parseLayers size (drop (length $ getData layer) img)
  | otherwise = []

main = do
  contents <- readFile "input8"
  print $ identifyLayer $ minimum $ parseLayers (25, 6) contents