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)

function main()
    divide = ["dream", "dreamer", "erase", "eraser"]

    S = chomp(readline())

    ans = true
    lenS = length(S)
    while lenS > 0
        is_contains = false
        for i = 1:4
            if length(divide[i]) <= lenS
                if S[lenS - length(divide[i]) + 1:lenS] == divide[i]
                    is_contains = true
                    lenS -= length(divide[i])
                end
            end
        end

        if !is_contains
            ans = false
            break
        end
    end

    if ans
        println("YES")
    else
        println("NO")
    end
end

main()