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 Ruby (2.7.1) (judge verdict: Wrong Answer)

t = gets.strip

# t = "PD?D??P"
# t = "P?P?"

arr = t.chars


loop do
  p arr

  i = 0
  loop do
    # p arr
    # p i
    c_prev = i > 0 ? arr[i-1] : nil
    c_curr = arr[i]
    c_next = i < (arr.length - 1) ? arr[i+1] : nil

    if c_curr == "?"
      if c_prev == "D" && c_next == "D"
        c_curr = "P"
      elsif c_prev == "D" && c_next == "P"
        c_curr = "D"
      elsif c_prev == "P" && c_next == "D"
        c_curr = "P"
      elsif c_prev == "P" && c_next == "P"
        c_curr = "D"
      elsif c_prev == "?" && c_next == "P"
        # c_prev = "P"
        arr[i-1] = "P"

        c_curr = "D"
      elsif c_prev == "?" && c_next == "D"
        c_curr = "P"
      elsif c_prev == "D" && c_next == "?"
        # Do nothing?
      elsif c_prev == "P" && c_next == "?"
        c_curr = "D"

      elsif c_prev == nil
        if c_next == "P"
          c_curr = "D"
        elsif c_next == "D"
          c_curr = "P"
        end
      elsif c_next == nil
        if c_prev != "?"
          c_curr = "D"
        end
      end

      arr[i] = c_curr if c_curr != "?"
    end
    
    i += 1
    break if i == arr.length
  end

  break if !arr.include?("?")
end

puts arr.join("")