content: import System.IO
  
  fac n = fac' n 1
    where fac' x r | x == 0 = r
                   | otherwise = fac' (x-1) (r*x)
  
  main = putStr "Bitte geben Sie eine Zahl ein: " >>
    hFlush stdout >>
    getLine >>=
    (\xStr ->
      let x = read xStr :: Int
      in putStr ("Die Fakultät von " ++ xStr ++ " ist: ") >> putStrLn (show $ fac x))
  