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)

S=reverse(chomp(readline()))
N=length(S)
id=1
while id<=N
	if id+4<=N&&S[id:id+4]=="maerd"
		id+=5
	elseif id+6<=N&&S[id:id+6]=="remaerd"
		id+=7
	elseif id+4<=N&&S[id:id+4]=="esare"
		id+=5
	elseif id+5<=N&&S[id:id+5]=="resare"
		id+=6
	else
		println("NO")
		exit()
	end
end
println("YES")