• Source 
    1. module Main where
    2.  
    3. main :: IO ()
    4. main = do
    5.   _ <- getLine
    6.   a <- getIntList
    7.   mapM_ putStrLn $ solve a
    8.  
    9. m :: [Int]
    10. m = [1, 0, -1, 0] ++ [0, 0 ..]
    11.  
    12. solve :: [Int] -> [String]
    13. solve a = fmt . loop $ reverse a
    14.   where
    15.   loop a' | length a' <= 4 = calc a'
    16.           | otherwise      = loop $ calc a'
    17.  
    18. fmt :: [Int] -> [String]
    19. fmt ns | s2 == []  = ["0", "0"]
    20.        | otherwise = [s1] ++ [s2]
    21.   where
    22.   ns' = dropWhile (==0) ns
    23.   s1 = show . pred $ length ns'
    24.   s2 = unwords . reverse $ map show ns'
    25.  
    26. calc :: [Int] -> [Int]
    27. calc ns = tail $ zipWith (-) ns $ map (* (head ns)) m
    28.  
    29. getIntList :: IO [Int]
    30. getIntList = map read . words <$> getLine