Problem:
Score : 300 points

Problem Statement

You are given a string S consisting of lowercase English letters.
Another string T is initially empty.
Determine whether it is possible to obtain S = T by performing the following operation an arbitrary number of times:

Append one of the following at the end of T: dream, dreamer, erase and eraser.

Constraints

1≦|S|≦10^5

S consists of lowercase English letters.

Input

The input is given from Standard Input in the following format:

S

Output

If it is possible to obtain S = T, print YES. Otherwise, print NO.

Sample Input 1

erasedream

Sample Output 1

YES

Append erase and dream at the end of T in this order, to obtain S = T.

Sample Input 2

dreameraser

Sample Output 2

YES

Append dream and eraser at the end of T in this order, to obtain S = T.

Sample Input 3

dreamerer

Sample Output 3

NO

Solution in C (GCC 9.2.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <string.h>
int main(void){
  char s[100000];
  char t[100000]; // maerd , remaerd , esare , resare 
  int s_length,i;
  scanf("%s",s);
  s_length = strlen(s);
  if(s_length < 5){
    printf("NO\n");
  }
  
  for(i=s_length-1;i>=0;i--){
    if(s[i]=='m'){
      t[i]='m'; t[i-1]='a'; t[i-2]='e'; t[i-3]='r'; t[i-4]='d';
      i=i-4;
    }else if(s[i]=='e'){
      t[i]='e'; t[i-1]='s'; t[i-2]='a'; t[i-3]='r'; t[i-4]='e';
      i=i-4;
    }else if(s[i-2]=='m'){
      t[i]='r'; t[i-1]='e'; t[i-2]='m'; t[i-3]='a'; t[i-4]='e';
      t[i-5]='r'; t[i-6]='d';
      i=i-6;
    }else if(s[i-2]=='s'){
      t[i]='r'; t[i-1]='e'; t[i-2]='s'; t[i-3]='a'; t[i-4]='r'; t[i-5]='e';
      i=i-5;
    }
  }
    if(strcmp(s,t)==0){
      printf("YES\n");
    }else{
      printf("NO\n");
    }

  return 0;
}