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 Java8 (OpenJDK 1.8.0) (judge verdict: Runtime Error)

package src;

import java.util.*;
class Main{
	static Scanner s = new Scanner(System.in);
	public static void main(String[] args) {
		StringBuilder str = new StringBuilder(s.next()
				.replaceAll("eraser", "")
				.replaceAll("dream", "D")
				.replaceAll("er", "R")
				.replaceAll("as", "A"));
		String[] m = {"RAe","DR","D"};
		String b,st;
		boolean f;
		do {
			f=false;
			for(int i=0;i<m.length;i++) {
				b=m[i];
				st = str.toString();
				if(st.endsWith(b)) {
					str.delete(str.length()-b.length(),str.length());
					f=true;
					break;
				}
			}
		}while(f);
		System.out.println((str.toString().equals(""))?"YES":"NO");
	}
}