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 Julia (1.4.0) (judge verdict: Accepted)

function main()
	str = chomp(readline())
	str = reverse(str)
	strArr = ["dream", "dreamer", "erase", "eraser"]
	strArr = map(reverse, strArr)
	
	while(true)
		cnt = 0
		for s in strArr
			if startswith(str, s)
				str = str[length(s)+1:end]
				cnt += 1
			end
		end

		if cnt < 1
			break
		end
	end
	
	print(str == "" ? "YES" : "NO" )
end

main()