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 JavaScript (node.js v5.12) (judge verdict: Wrong Answer)

"use strict";
const main = arg => {
  let word = arg.trim();
  let judge　= "NO";
  let isRoop = true;
  roop:
  while(isRoop){
    switch (word.substr(-3, 3)){
      case 'eam':
        // 5文字分削る
        word = word.slice(0,-5);
        break;
      case 'mer':
        word = word.slice(0,-7);
        break;
      case 'ase':
        word = word.slice(0,-5);
        break;
      case 'ser':
        word = word.slice(0,-6);
        break;
      default:
        isRoop = false;
        break roop;
    }
  }
  if(word.length == 0){
  judge = "YES"
  }
  console.log(judge);
}

main(require('fs').readFileSync('/dev/stdin', 'utf8'));