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: Accepted)

import sys
sys.setrecursionlimit(10000000)
import numpy as np
from heapq import heapify, heappop, heappush
import copy
from math import gcd, ceil
from collections import deque
# queueとして使う場合 push, popleftを使う
from bisect import bisect_left, bisect_right
# bisect_left: 配列の順序関係が崩れない条件で挿入することができる一番左の点
# bisect_right: 配列の順序関係が崩れない条件で挿入することができる一番右の点
# A = [1, 1, 1, 2, 2, 2, 4]
# print(bisect_left(A, 2))  # 3
# print(bisect_right(A, 2))  # 6
# print(bisect_left(A, 3))  # 6
# print(bisect_right(A, 3))  # 6


def main():
    S = input()
    if len(S) == 1 and S == '?':
        print('D')
        sys.exit()
    i = 0
    S = list(S)
    while i < len(S):
        if S[i] == '?':
            if i == 0:
                if S[1] == '?':
                    S[0] = 'P'
                    S[1] = 'D'
                    i = 2
                    continue
                elif S[1] == 'D':
                    S[0] = 'P'
                    i = 2
                    continue
                else:
                    S[0] = 'D'
                    i = 2
                    continue
            else:
                if i + 1 == len(S):
                    S[i] = 'D'
                    i += 1
                    continue
                elif S[i - 1] == 'P':
                    S[i] = 'D'
                    i += 1
                    continue
                elif S[i + 1] == '?':
                    S[i] = 'P'
                    S[i + 1] = 'D'
                    i = i + 2
                    continue
                elif S[i + 1] == 'D':
                    S[i] = 'P'
                    i += 1
                    continue
                else:
                    S[i] = 'D'
                    i += 1
        else:
            i += 1
    print(''.join(S))
            

if __name__ == '__main__':
    main()