#include<stdio.h>
int main(void){
char s[2000100];
  int i=0;
  while(1){
	 	scanf("%c",&s[i]);
    	if(s[i]=='\0')return 0;
        if(s[i]=='?')printf("D");
    	else printf("%c",s[i]);
    	i++;
  }
  return 0;
}