import Data.List

main :: IO ()
main = do
  input <- readFile "input"
  let stones = map readInt . words . init $ input
--  print $ part1 stones
  print $ part2 stones

----

part2 ns =
  let nns = map (\n -> (1,n)) ns
      x = (iterate blinkC nns)!!75
  in sum $ map fst x

blinkC ns = compress $ sortOn snd $ concatMap blinkC1 ns

blinkC1 (n,m) = map (\k -> (n,k)) (blink1 m)

compress :: Eq a => [(Int,a)] -> [(Int,a)]
compress [] = []
compress [x] = [x]
compress ((n1,m1):(n2,m2):rest)
  | m1 == m2 = compress ((n1+n2,m1):rest)
  | otherwise = (n1,m1):(compress ((n2,m2):rest))

----

part1 ns = length $ (iterate blink ns)!!25

blink ns = concatMap blink1 ns

blink1 0 = [1]
blink1 n =
  let s = show n
      l = length s
  in if even l then map readInt $ pairToList $ splitAt (l `div` 2) s
     else [n*2024]

pairToList (a,b) = [a,b]

readInt :: String -> Integer
readInt = read