#include<stdio.h>

int main(void){
  int i;
  char c, t[200001];
  i = 0;
  while((c = getchar()) != EOF){
    if(c == '?'){
      t[i++] = 'D';
    }
    else{
      t[i++] = c;
    }
  }
  t[i] = '\0';
  
  printf("%s", t);
  
  return 0;
}
