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# (.NET Core 3.1.201) (judge verdict: Time Limit Exceeded)

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Xml.Schema;
using System.Text.RegularExpressions;

namespace contest_Csharp
{
    class Program
    {
        static List<string> pattern = new List<string>();
        static Regex re = new Regex("\\?");
        static void Main(string[] args)
        {

            var input1 = System.Console.ReadLine();
            Replase(input1);
            int max = 0;
            string maxText = "";
            foreach(var text in pattern)
            {
                var count = Count(text);
                if(max < count)
                {
                    max = count;
                    maxText = text;
                }
            }

            Console.WriteLine(maxText);

        }

        static void Replase(string text)
        {
            if(text.IndexOf("?")  == -1)
            {
                pattern.Add(text);
                return;
            }

            Replase(re.Replace(text, "D", 1));
            Replase(re.Replace(text, "P", 1));
        }

        static int Count(string text)
        {
            int count = 0;
            char pre = ' ';
            for (int i = 0; i < text.Length; i++)
            {
                if(text[i] == 'D')
                {
                    count++;
                }
                
                if(pre == 'P' && text[i] == 'D')
                {
                    count++;
                }

                pre = text[i];
            }

            return count;
        }
    }
}