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: Wrong Answer)

import java.util.Scanner;

/**
 *
 * @author psygn
 */
public class Main {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        String str = scanner.nextLine();
        String ans = "NO";
        str = str.replace("dreamer", "[space]");
        str = str.replace("dream", "[space]");
        str = str.replace("eraser", "[space]");
        str = str.replace("erase", "[space]");
        str = str.replace("[space]", "");
        if ("".equals(str)){
            ans = "YES";
        }
        System.out.println(ans);
    }
}