n_ ""           = 0
n_ ('M':xs)     = 1000 + n_ xs
n_ ('C':'D':xs) = 400 + n_ xs
n_ ('C':'M':xs) = 900 + n_ xs
n_ ('D':xs)     = 500 + n_ xs
n_ ('C':xs)     = 100 + n_ xs
n_ ('X':'L':xs) = 40 + n_ xs
n_ ('X':'C':xs) = 90 + n_ xs
n_ ('L':xs)     = 50 + n_ xs
n_ ('X':xs)     = 10 + n_ xs
n_ "IV"         = 4
n_ "IX"         = 9
n_ ('V':xs)     = 5 + n_ xs
n_ xs           = length xs

m x
  | x >= 4000 = "ERROR"
  | otherwise = s4 ++ s3 ++ s2 ++ s1
  where
    [x1, x2, x3, x4] = take 4 $ map (`mod` 10) (iterate (`div` 10) x) ++ replicate 4 0
    f u1 u2 u3 x = if x == 9
                   then [u1, u3]
                   else if x >= 5
                        then u2 : replicate (x - 5) u1
                        else if x == 4
                             then [u1, u2]
                             else replicate x u1
    s4 = replicate x4 'M'
    s3 = f 'C' 'D' 'M' x3
    s2 = f 'X' 'L' 'C' x2
    s1 = f 'I' 'V' 'X' x1

main = do
  _ <- getLine
  rs <- words <$> getLine
  let s = sum $ map n_ rs
  putStrLn $ m s