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 PHP (7.4.4) (judge verdict: Wrong Answer)

<?php
fscanf(STDIN, "%s", $s);
$s= strrev($s);
$array = array("dream","dreamer","erase","eraser");
foreach($array as $k => $v){
  $array[$k] = strrev($v);
}
$ans = true;
for($i=0;$i<=strlen($s);){
  $ansz = false;
  foreach($array as $v){
    if(strpos($s,$v,$i)===$i){
      $i += strlen($v);
      $ansz = true;
    }
  }
  if($ansz == false){
    $ans = false;
    break;
  }
}
  if($ans == true){
    echo "YES";
  }else{
    echo "NO";}
  
?>