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: Accepted)

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;

namespace ForATCODER
{
    public class Program
    {
        ///template
        ///
        /// String[] s = Console.ReadLine().Split(' ');
        ///   long[] nk =  s2larray(Console.ReadLine().Split(' '));
        ///   

        public static void Main(string[] args)
        {
            String T = Console.ReadLine();
            System.Text.StringBuilder T2 = new System.Text.StringBuilder(T);
            /*   int p = T.Count(x=> x=='P');
               int d = T.Count(x => x == 'D');
               int q = T.Count(x => x == '?');*/
            // PD count
         /*   for (int i = 0; i < T2.Length; i++)
            {
                char c1 = T2[i];
                char c2='\0';
                if (i < T2.Length - 1)  c2 = T2[i+1];
               if(c1=='P' && c2=='D')
                {
                    point += 2;
                    T = T.Remove(i-count,2);
                    count+=2;
                }
            }*/

            T2 = new System.Text.StringBuilder(T);
            for (int i = 0; i < T2.Length; i++)
            {
                char c1 = T2[i];
                char c2 = '\0';
                if (i < T2.Length - 1) c2 = T2[i + 1];
                if (c1 == '?' && c2 == 'D')
                {
                    T2[i] = 'D';
                } else if (c1 == '?')
                {
                    T2[i] = 'D';
                }
            }
         /*   T = T2.ToString();
            for (int i = 0; i < T2.Length; i++)
            {
                char c1 = T2[i];
                char c2 = '\0';
                if (i < T2.Length - 1) c2 = T2[i + 1];
                if (c1 == 'P' && c2 == 'D')
                {
                    point += 2;
                    T = T.Remove(i - count, 2);
                    count += 2;
                }
            }*/
      //     point += T.Count(x=>x=='D');
            RESULT(T2.ToString());
        }
 
        static void addarray(long[] arr ,int start,int end)
        {
            for(int i = start; i <= end;i++)
            {
                arr[i]++;
            }
        }
        public static decimal Sqrt(decimal x)
        {
            decimal sqrt_x = (decimal)Math.Sqrt((long)x);
            for (int i = 0; i < 10; ++i)
                sqrt_x = 0.5m * (sqrt_x + x / sqrt_x);
            return sqrt_x;
        }
        static   long summ(long s)
        {
            if (s == 1) return 1;
            return s + summ(s-1);
        }
        public static bool checka(int[] a, int m)
        {
            int back = 1;
            for (int i = 0; i < a.Length; i++)
            {
                if (a[i] >= 1 && a[i] <= m)
                {
                    if (a[i] >= back)
                    {
                        back = a[i];
                    }
                    else
                    {
                        return false;
                    }
                }
                else
                {
                    return false;
                }
            }
            return true;
        }
        public static ulong pow(int a, int b)
        {
            ulong res = 1;
            for (int i = 0; i < b; i++)
            {
                res *= (ulong)a;
            }
            return res;
        }
        static int s2i(String s)
        {
            return Convert.ToInt32(s);
        }
        static long s2l(String s)
        {
            return Convert.ToInt64(s);
        }
        static void RESULT(double res)
        {
            Console.WriteLine(res);
        }
        static void RESULT(long res)
        {
            Console.WriteLine(res);
        }
        static void RESULT(ulong res)
        {
            Console.WriteLine(res);
        }
        static void RESULT(int res)
        {
            Console.WriteLine(res);
        }
        static void RESULT(String res)
        {
            Console.WriteLine(res);
        }
        static String[] ReadLineAll(int count)
        {
            String[] res = new String[count];
            for (int i = 0; i < count; i++)
            {
                res[i] = Console.ReadLine();
            }
            return res;
        }

        static int[] s2iarray(String[] src)
        {
            int len = src.Length;
            int[] res = new int[len];
            for (int i = 0; i < len; i++)
            {
                res[i] = Convert.ToInt32(src[i]);
            }
            return res;
        }
        static long[] s2larray(String[] src)
        {
            int len = src.Length;
            long[] res = new long[len];
            for (int i = 0; i < len; i++)
            {
                res[i] = Convert.ToInt64(src[i]);
            }
            return res;
        }
        static ulong[] s2larray2(String[] src)
        {
            int len = src.Length;
            ulong[] res = new ulong[len];
            for (int i = 0; i < len; i++)
            {
                res[i] = Convert.ToUInt64(src[i]);
            }
            return res;
        }

        static long C(int n, int r)
        {
            if (n <= 1) return 0;
            if (r > n - r) r = n - r; // because C(n, r) == C(n, n - r)
            long ans = 1;
            int i;

            for (i = 1; i <= r; i++)
            {
                ans *= n - r + i;
                ans /= i;
            }

            return ans;
        }
        static long C(long n, long r)
        {
            if (n <= 1) return 0;
            if (r > n - r) r = n - r; // because C(n, r) == C(n, n - r)
            long ans = 1;
            int i;

            for (i = 1; i <= r; i++)
            {
                ans *= n - r + i;
                ans /= i;
            }

            return ans;
        }
        static ulong C(ulong n, ulong r)
        {
            if (n <= 1) return 0;
            if (r > n - r) r = n - r; // because C(n, r) == C(n, n - r)
            ulong ans = 1;
            ulong i;

            for (i = 1; i <= r; i++)
            {
                ans *= n - r + i;
                ans /= i;
            }

            return ans;
        }
   
    
    }

}