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 Java (OpenJDK 11.0.6) (judge verdict: Time Limit Exceeded)



import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String t = sc.next();
		if (t.equals("?")) {
			System.out.println("D");
			return;
		}
		boolean next = false;
		int length = 0;
		for (int i = 0; i < t.length(); i++) {
			boolean is = false;
			if (next) {
				next = false;
				continue;
			}
//			if (i!= t.length()-1 && t.charAt(i) == '?' && t.charAt(i+1) == '?') {
//				length+=1;
//			}

			if (t.charAt(i) == '?') {
				if (i >= 1) {
					if (t.charAt(i-1) == 'P') {
						StringBuilder stringBuilder = new StringBuilder(t);
						stringBuilder.setCharAt(i, 'D');
						t = stringBuilder.toString();
						is = true;
					} else if (i == t.length()-1) {
						StringBuilder stringBuilder = new StringBuilder(t);
						stringBuilder.setCharAt(i, 'D');
						t = stringBuilder.toString();
						is = true;
					}
				}
				if (i != t.length()-1 && !is) {
					if (t.charAt(i+1) == 'D' || t.charAt(i+1) == '?') {
						StringBuilder stringBuilder = new StringBuilder(t);
						stringBuilder.setCharAt(i, 'P');
						stringBuilder.setCharAt(i+1, 'D');
						t = stringBuilder.toString();
						next = true;
					} else {
						StringBuilder stringBuilder = new StringBuilder(t);
						stringBuilder.setCharAt(i, 'D');
						t = stringBuilder.toString();
					}
				}
			}
		}
		System.out.println(t);
	}

}