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: Wrong Answer)

using System;
using System.IO;
using System.Linq;
using System.Collections.Generic;
using System.Text;
using System.Numerics;

namespace nomura2020
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });
            if (File.Exists("input.txt"))
            {
                Console.SetIn(new StreamReader("input.txt"));
            }
            solve_nomura2020B();
            Console.Out.Flush();
        }

        public static void solve_nomura2020B()
        {
            char[] s = Console.ReadLine().ToCharArray();
            int cnt = 0;
            Stack<Tuple<char, int>> stk = new Stack<Tuple<char, int>>();
            char prev = '@';
            for (int i = s.Length - 1; i >= 0; i--)
            {
                if (s[i] == '?')
                {
                    cnt++;
                }
                if (prev == '@' && s[i] != '?')
                {
                    prev = s[i];
                }
                if (cnt > 0 && (s[i] == 'D' || i == 0))
                {
                    stk.Push(Tuple.Create(prev, cnt));
                    cnt = 0;
                    prev = s[i];
                }
                if (cnt > 0 && (s[i] == 'P'|| i == 0))
                {
                    stk.Push(Tuple.Create(prev, cnt));
                    cnt = 0;
                    prev = s[i];
                }
            }

            int k = 0;
            while (k < s.Length)
            {
                if (s[k] == '?')
                {
                    if (stk.Count > 0)
                    {
                        var r = stk.Peek();
                        if (r.Item2 % 2 == 0)
                        {
                            int z = 0;
                            while (z < r.Item2) 
                            {
                                if (z % 2 == 0)
                                {
                                    s[k + z] = 'P';
                                }
                                else
                                {
                                    s[k + z] = 'D';
                                }
                                z++;
                            }
                            k += z;
                        }
                        else
                        {
                            int z = 0;
                            char fst = 'D';
                            char snd = 'P';
                            if (r.Item1 == 'D')
                            {
                                fst = 'P';
                                snd = 'D';
                            }
                            while (z < r.Item2) 
                            {
                                if (z % 2 == 0)
                                {
                                    s[k + z] = fst;
                                }
                                else
                                {
                                    s[k + z] = snd;
                                }
                                z++;
                            }
                            k += z;
                        }
                        stk.Pop();
                    }
                }
                else
                {
                    k++;
                }
            }
            Console.WriteLine(new string(s));
        }

        public static void solve_nomura2020A()
        {
            int[] t = Array.ConvertAll(Console.ReadLine().Split(), int.Parse);
            Console.WriteLine(Math.Abs(Math.Abs(t[0] * 60 + t[1] - (t[2] * 60 + t[3])) - t[4]));
        }
    }
}