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 12.16.1) (judge verdict: Wrong Answer)

// https://atcoder.jp/contests/abc049/tasks/arc065_a

function main(arg) {
  const S = arg;
  
  const s = S.replace(/dream(er(aser?)?)?|eraser?/g, '');
  if (s == '') {
    console.log('YES');
  } else {
    console.log('NO');
  }
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));