rome num pos s = do
    let myVal = rv !! pos
    if myVal <= num
        then do
            rome (num - myVal) pos (s ++ (rc !! pos))
        else if num > 0
            then rome num (pos + 1) s
            else putStrLn s
    where
        rc = ["M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"]
        rv = [1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1]

main = do
    putStrLn "Zahl: "
    n <- getLine
    rome (read n) 0 "Ergebnis: "