import Data.Char
import Data.List

type Parser a = String -> [(a, String)]

char :: Parser Char
char [] = []
char (x:xs) = [(x, xs)]

failure :: Parser a
failure = (\a -> [])

return :: Parser a
return v inp = [(v, inp)]

parse :: Parser a -> String -> [(a, String)]
parse p inp = p inp

main :: IO ()
main = do
  inputLines <- lines <$> getContents

  -- let arePossible = filter isPossible lines

  mapM_ putStrLn inputLines