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: Time Limit Exceeded)

function Main(input){
  var S = input[0].toString();
  
  var revS = S.split('').reverse().join('');
  var divide = ['dream', 'dreamer', 'erase', 'eraser'].map(s => {
    return s.split('').reverse().join('');
  });
  
  var stringN = 0;
  
  while(stringN < revS.length){
    var word = divide.find(w => {
      return revS.startsWith(w, stringN);
    });
    
    if(!word){
      console.log('NO');
    } else {
      stringN += word.length;
    }
  }
  
  console.log('YES');
}

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