Problem:
Score : 200 points

Problem Statement

For a string S consisting of the uppercase English letters P and D, let the doctoral and postdoctoral quotient of S be the total number of occurrences of D and PD in S as contiguous substrings. For example, if S = PPDDP, it contains two occurrences of D and one occurrence of PD as contiguous substrings, so the doctoral and postdoctoral quotient of S is 3.

We have a string T consisting of P, D, and ?.

Among the strings that can be obtained by replacing each ? in T with P or D, find one with the maximum possible doctoral and postdoctoral quotient.

Constraints

1 \leq |T| \leq 2 \times 10^5

T consists of P, D, and ?.

Input

Input is given from Standard Input in the following format:

T

Output

Print one string with the maximum possible doctoral and postdoctoral quotient among the strings that can be obtained by replacing each ? in T with P or D.
If there are multiple such strings, you may print any of them.

Sample Input 1

PD?D??P

Sample Output 1

PDPDPDP

This string contains three occurrences of D and three occurrences of PD as contiguous substrings, so its doctoral and postdoctoral quotient is 6, which is the maximum doctoral and postdoctoral quotient of a string obtained by replacing each ? in T with P or D.

Sample Input 2

P?P?

Sample Output 2

PDPD

Solution in Haskell (GHC 8.8.3) (judge verdict: Wrong Answer)

import qualified Data.Text as T
import qualified Data.Text.IO as T
import qualified Data.Text.Read as T
import Data.Bool (bool)

main :: IO ()
main = do
  let
    f :: [Bool] -> (([Bool], Int), ([Bool], Int))
    f = ((,) <$> snd . fst <*> snd) . foldr step ((True, ([], 0)), ([], 0))
      where
        step :: Bool -> ((Bool, ([Bool], Int)), ([Bool], Int)) -> ((Bool, ([Bool], Int)), ([Bool], Int))
        step False ((_, (kt, ki)), m) = ((False, (False : kt, 1 + ki)), m)
        step True ((False, (kt, ki)), m) = ((True, (True : kt, 1 + ki)), m)
        step True ((True, k@(_, ki)), m@(_, mi)) = ((True, ([], 0)), bool k m (ki <= mi))
  t <- map (== 'P') <$> getLine :: IO [Bool]
  let
    ((kt, ki), (mt, mi)) = f t :: (([Bool], Int), ([Bool], Int))
  putStrLn . map (bool 'D' 'P') $ bool kt mt (ki <= mi)

unsafeTextToInt :: T.Text -> Int
unsafeTextToInt s = case T.signed T.decimal s of
  Right (n, _) -> n
{-# INLINE unsafeTextToInt #-}