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 (7.3.0) (judge verdict: Time Limit Exceeded)

S = input()
S = S[::-1]
candidacies = ["dream", "dreamer", "erase", "eraser"]
candidacies = [c[::-1] for c in candidacies]

fi_flg = False
while fi_flg is False:
  if S[:6] in candidacies:
    S = S[6:]
  elif S[:5] in candidacies:
    S = S[5:]
  elif S[:7] in candidacies:
    S = S[:7]
  else:
    fi_flg = True

if len(S) == 0:
  print("YES")
else:
  print("NO")