import System.Random

maxC = 23

data CardState = CardState { num0  :: Int
                           , num1  :: Int
                           , cards :: [Int]
                           } deriving (Show)

makeList :: [Int] -> CardState -> CardState
makeList (x:xs) n | n0 >= maxC && n1 >= maxC = n
                  | n0 >= maxC && x == 0    = makeList xs n
                  | n1 >= maxC && x == 1    = makeList xs n
                  | x == 0 = makeList xs $ CardState (n0 + 1) n1 (cs ++ [x])
                  | x == 1 = makeList xs $ CardState n0 (n1 + 1) (cs ++ [x])
  where n0 = num0 n
        n1 = num1 n
        cs = cards n

checkWin (x:xs) | length xs <= 2         = x == 0
                | x == 1 && xs !! 1 == 1 = xs !! 2 == 0
                | otherwise              = checkWin xs

runTrial = do g <- newStdGen
              let xs  = randomRs (0,1) g :: [Int]
              let xs' = makeList xs (CardState 0 0 [])
              return $ checkWin (cards xs')

main = do xs <- mapM (\x -> runTrial) [1..10000]
          print $ fromIntegral (length (filter (==True) xs)) / fromIntegral (length xs)