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 JavaScript (Node.js 12.16.1) (judge verdict: Wrong Answer)

function Main(input) {
  // 1行目がinput[0], 2行目がinput[1], …に入る
  input = input.split("\n");

  var S = input[0];
  var arr = PorD( S );
  var max = -1;
  var ans = '';
  for( var i = 0; i < arr.length; i ++ ){
    var cnt = count( arr[i] );
    if( cnt > max ){
      cnt = max;
      ans = arr[i];
    }
  }
  
  console.log( ans );
}

function count( str ){
  var cnt = 0;
  for( var i = 0; i < str.length; i ++ ){
    if( str.charAt( i ) == 'D' ){
      cnt ++;
    }
  }
  for( var i = 0; i < str.length - 1; i ++ ){
    if( str.charAt( i ) == 'P' && str.charAt( i + 1 ) == 'D' ){
      cnt ++;
    }
  }
  
  return cnt;
}

function PorD( str ){
  var arr = [ str ];
  var idxs = [];

  for( var i = 0; i < str.length; i ++ ){
    if( str.charAt( i ) == '?' ){
      idxs.push( i );
    }
  }
  
  for( var i = 0; i < idxs.length; i ++ ){
    var arr0 = [];
    while( arr.length > 0 ){
      var s = arr.pop();
      var s1 = s.substr( 0, idxs[i] ) + 'P' + s.substr( idxs[i] + 1 );
      var s2 = s.substr( 0, idxs[i] ) + 'D' + s.substr( idxs[i] + 1 );
      arr0.push( s1 );
      arr0.push( s2 );
    }
    //arr = JSON.parse( JSON.stringify( arr0 ) );
    arr = arr0;
  }
      
  return arr;
}

//*この行以降は編集しないでください（標準入出力から一度に読み込み、Mainを呼び出します）
Main(require("fs").readFileSync("/dev/stdin", "utf8"));