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: Wrong Answer)

# function erase(s::string, ur::UnitRange)
#     res = ""
#     if(ur.start != 1)
#         res *= s[1:ur.start - 1]
#     end

#     if(ur.stop != length(s))
#         res *= s[ur.stop + 1:end]
#     end

#     return res
# end

function main()
    divide = ["dream", "dreamer", "erase", "eraser"]
    divide = map(x -> x = reverse(x), divide)

    S = reverse(readline())

    can = true
    i = 1
    while 1 <= i <= length(S)
        can2 = false
        for j = 1:4
            d = divide[j]
            if length(S) >= i + length(d) - 1 && S[i:i + length(d) - 1] == d
                can2 = true
                i += length(d)
            end
        end
        if !can2
            can = false
            break
        end
    end

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

main()