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'

function main(input) {
  let s = input

  while(true) {
    if (s.endsWith('dream') || s.endsWith('erase')) {
      s = s.slice(0, -5)
    } else if (s.endsWith('eraser')) {
      s = s.slice(0, -6)
    } else if (s.endsWith('dreamer'))  {
      s = s.slice(0, -7)
    } else {
      break
    }
  }

  if (s.length === 0) {
    console.log('YES')
  } else {
    console.log('NO')
  }
}

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