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 Python (3.8.2) (judge verdict: Time Limit Exceeded)

import sys
sys.setrecursionlimit(100000)


S = ""
LENGTH = -1


def process(i, pd_count, d_count, last, K):
    if i >= LENGTH:
        return pd_count + d_count, K

    s = S[i]
    if last == "P":
        if s == "D":
            pd_count += 1
            d_count += 1
            return process(i+1, pd_count, d_count, s, K + "D")
        elif s == "P":
            # 連続終わり
            return pd_count + d_count, K + "P"
        elif s == "?":
            # ?=Pよりは?=Dの方が常にスコア高い
            return process(i+1, pd_count+1, d_count+1, "D", K + "D")
    elif last == "D":
        if s == "D":
            return process(i+1, pd_count, d_count+1, s, K + "D")
        elif s == "P":
            return process(i+1, pd_count, d_count, s, K + "P")
        elif s == "?":
            s1, K1 = process(i+1, pd_count, d_count+1, "D", K + "D")
            s2, K2 = process(i+1, pd_count, d_count, "P", K + "P")
            if s1 > s2:
                return s1, K1
            else:
                return s2, K2
    elif last == "":
        if s == "D":
            return process(i+1, 0, 1, s, K + "D")
        elif s == "P":
            return process(i+1, 0, 0, s, K + "P")
        elif s == "?":
            s1, K1 = process(i+1, 0, 1, "D", K + "D")
            s2, K2 = process(i+1, 0, 0, "P", K + "P")
            if s1 > s2:
                return s1, K1
            else:
                return s2, K2


S = input()
subSs = []
while True:
    pos = S.find("PP")
    if pos == -1:
        subSs.append(S)
        break
    subS = S[:pos+1]
    subSs.append(subS)
    S = S[pos+1:]


score = 0
K = ""
for S in subSs:
    LENGTH = len(S)
    subScore, subK = process(0, 0, 0, "", "")
    K += subK
print(K)