import Data.List

main :: IO ()
main = putStr
     . unlines
     . map show
     . filter (isPandigital . toRoman)
     $ [1..2000]

toRoman :: Int -> String
toRoman = toRoman'
  [ (1000, "M"), (900, "CM"), (500, "D"), (400, "CD")
  , (100, "C"), (90, "XC"), (50, "L"), (40, "XL")
  , (10, "X"), (9, "IX"), (5, "V"), (4, "IV"), (1, "I")
  ]
  where
    toRoman' :: [(Int, String)] -> Int -> String
    toRoman' _          0 = ""
    toRoman' []         _ = error "Empty roman numerals"
    toRoman' ((y,r):ys) x
      | x < y             = toRoman' ys x
      | otherwise         = r ++ toRoman' ((y,r):ys) (x - y)

isPandigital :: String -> Bool
isPandigital = (== "CDILMVX") . sort