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 (0.5.0) (judge verdict: Accepted)

drm(x) = x=="dream"?true:false
drme(x) = x=="dreamer"?true:false
ers(x) = x=="erase"?true:false
erse(x) = x=="eraser"?true:false


function main()
	x = chomp(readline())
	t = length(x)
	flg = 0
	while t > 0
		if t <= 4
			flg = 1
			break
		elseif drm(x[t-4:t]) || ers(x[t-4:t])
			t -= 5
		elseif t <= 5
			flg = 1
			break
		elseif erse(x[t-5:t])
			t -= 6
		elseif t <= 6
			flg = 1
			break
		elseif drme(x[t-6:t])
			t -= 7
		else
			flg = 1
			break
		end
	end
	if flg == 1
		print("NO")
	else
		print("YES")
	end
end

main()