Huiaskel 1-17

import Control.Monad
import qualified Data.ByteString.Char8 as B
import Data.Maybe
import Data.List
import Control.Arrow

readInt :: B.ByteString -> Int
readInt = fst . fromJust . B.readInt

main :: IO ()
main = do
  [n] <- liftM (map readInt . B.words) B.getLine
  lst <- liftM (map readInt . take n . B.words) B.getLine :: IO [Int]
  let res = remove_val_index_match lst (n - 1)
  putStrLn "Input: "
  print lst
  putStrLn "Result: "
  print res


erase idx xs = lft ++ rgt
  where (lft, (_:rgt)) = splitAt idx xs


remove_val_index_match []  k = []
remove_val_index_match lst k | k <= -1        = lst
                             | (lst!!k) ==  k = remove_val_index_match (erase k lst) (k - 1)
                             | otherwise      = remove_val_index_match lst (k - 1)

-- 6
-- 0 4 2 3 5 7