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 = "X" * chomp(readline())
function letter(S)
    if S[end-4:end] == "dream" || S[end-4:end] == "erase"
        return S = S[1:end-5]
    elseif S[end-5:end] == "eraser"
        return S = S[1:end-6]
    elseif S[end-6:end] == "dreamer"
        return S = S[1:end-7]
    end
end

for i in 1:25000
    try
        S = letter(S)
    except
        break
    end
end

if S == "X"
    println("YES")
else
    println("NO")
end