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 Python (3.4.3) (judge verdict: Wrong Answer)

s=input()

s=s[::-1]

X=['maerd','remaerd','esare','resare']
ans='Yes'
i=0
while i<=len(s)-5:
    if s[i:i+5] in X:
        i+=5
    else:
        if s[i:i+6] in X:
            i+=6
        else:
            if s[i:i+7]  in X:
                i+=7
            else:
                ans='No'
                break

print(ans)