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 C++ (GCC 9.2.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<int, int> i_i;

#define reps(i,s,n) for(int i = s; i < n; i++)
#define rep(i,n) reps(i,0,n)
#define ALL(v) v.begin(), v.end()
#define SZ(x) ((int)(x).size())
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }


int V, E;
const int MAX_V = 3e5 + 5;
using DD = int;
#define INF 1e9+7
DD d[MAX_V];
struct edge {int to; DD cost; };
vector<edge> G[MAX_V];

int pprev[MAX_V];

int R[200005];
int main() {
    string S, T;
    
    cin >> S;
    T = S;
    
    int renzoku = 0;
    for (int i = S.size() - 1; i >= 0; i--){
        if (S[i] == '?'){
            renzoku++;
        } else {
            renzoku = 0;
        }
        R[i] = renzoku;
    }
    rep(i, S.size()){
        if (S[i] == '?'){
            char next = i < S.size() ? S[i + R[i]]: '0';
            char prev = i > 0 ? S[i - 1]: '0';
            //fprintf(stderr, "%d: r %d, %c, %c\n", i, R[i], prev, next);
            if (prev == 'P'){
                T[i] = 'D';
            } else if (next == 'D'){
                if (R[i] % 2 == 1){
                    T[i] =  'P';
                } else {
                    T[i] =  'D';
                }
            } else if (R[i] % 2 == 0){
                T[i] = 'P';
            } else {
                T[i] = 'D';
            }
        }
    }
    cout << T;
    return 0;
}