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 PyPy3 (2.4.0) (judge verdict: Accepted)

def slove():
    import sys
    input = sys.stdin.readline
    s = str(input().rstrip('\n'))
    s = s.replace("eraser", "").replace("erase", "").replace("dreamer", "").replace("dream", "")
    print("YES" if s == "" else "NO")


if __name__ == '__main__':
    slove()