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 Scala (2.13.1) (judge verdict: Wrong Answer)

import java.util.Scanner

object Main extends App {
  val sc = new Scanner(System.in)
  var s = sc.nextLine()

  s = s.replace("dreamer","").replace("eraser","").
    replace("dream","").replace("erase","")
  if (s.length == 0) {
    println("YES")
  } else {
    println("NO")
  }
}