import Control.Applicative
import Data.ByteString.Char8 (ByteString)
import qualified Data.ByteString.Char8 as B

main :: IO ()
main = solve <$> B.getLine >>= B.putStrLn

solve :: ByteString -> ByteString
solve = B.map f
  where
    f '?' = 'D'
    f x = x
