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.Linq;
using System.Collections.Generic;
using System.Runtime.InteropServices.ComTypes;
using System.Security.Cryptography.X509Certificates;
using System.Numerics;

namespace Atcoder01
{
    class Program
    {
        static void Main(string[] args)
        {
            string T = Onestring();
            string ans = "";
            for(int i = 0; i < T.Length; i++)
            {
                string a = T.Substring(i, 1);
                if (T.Substring(i,1) == "?")
                {
                    a = "D";
                }
                ans += a;
            }
            	Console.WriteLine(ans);
        }

        static double Mathing(double a, double b,double num)
        {
            double xlog = Math.Log(num);
            double result = Math.Pow(a, 2+xlog) + b*num;
            return result;
        }

        static string Tasu(string a1, string b1)
        {
            int anum = a1.Length;
            int bnum = b1.Length;
            int[] a = Array(a1);
            int[] b = Array(b1);

            string tasustring = "";
            if (anum < bnum)
            {
                int[] tasuans = new int[bnum + 1];
                for (int i = 0; i < anum; i++)
                {
                    tasuans[i] = a[i] + b[i];
                }
                for (int i = anum; i < bnum; i++)
                {
                    tasuans[i] = b[i];
                }
                for (int i = 0; i < tasuans.Length; i++)
                {
                    if (tasuans[i] >= 10)
                    {
                        tasuans[i] -= 10;
                        tasuans[i + 1]++;
                    }
                }
                for (int i = 0; i < tasuans.Length - 1; i++)
                {
                    tasustring = tasuans[i].ToString() + tasustring;
                }
                if (tasuans[tasuans.Length - 1] != 0)
                {
                    tasustring = tasuans[tasuans.Length - 1].ToString() + tasustring;
                }
            }
            else
            {
                int[] tasuans = new int[anum + 1];
                for (int i = 0; i < bnum; i++)
                {
                    tasuans[i] = a[i] + b[i];
                }
                for (int i = bnum; i < anum; i++)
                {
                    tasuans[i] = a[i];
                }
                for (int i = 0; i < tasuans.Length; i++)
                {
                    if (tasuans[i] >= 10)
                    {
                        tasuans[i] -= 10;
                        tasuans[i + 1]++;
                    }
                }
                for (int i = 0; i < tasuans.Length - 1; i++)
                {
                    tasustring = tasuans[i].ToString() + tasustring;
                }
                if (tasuans[tasuans.Length - 1] != 0)
                {
                    tasustring = tasuans[tasuans.Length - 1].ToString() + tasustring;
                }
            }
            return tasustring;
        }

        static int[] Array(string A)
        {
            int[] a = new int[A.Length];
            string num;
            for (int i = 0; i < A.Length; i++)
            {
                num = A.Substring(i, 1);
                a[A.Length - i - 1] = int.Parse(num);
            }

            return a;
        }


        private static string[] Arraystring()
        {
            return Console.ReadLine().Split(' ');
        }

        private static string Onestring()
        {
            return Console.ReadLine();
        }

        private static int Oneint()
        {
            return int.Parse(Console.ReadLine());
        }

        private static int[] Arrayint()
        {
            return Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
        }

        private static long Onelong()
        {
            return long.Parse(Console.ReadLine());
        }

        static long[] Arraylong()
        {
            String[] input_line = Console.ReadLine().Split(' ');
            long[] input_num = new long[input_line.Length];
            for (int i = 0; i < input_line.Length; i++)
            {
                input_num[i] = long.Parse(input_line[i]);
            }
            return input_num;
        }
    }
}