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 LuaJIT (2.0.4) (judge verdict: Accepted)

local long_str = io.read("*l")
local tmps = {"dream", "dreamer", "erase", "eraser"}

long_str = long_str:reverse()
for i = 1, #tmps do
    tmps[i] = string.reverse(tmps[i])
end

local index = 1
local is_none = false
while index < long_str:len() do
    local old_index = index
    for i = 1, #tmps do
        local tmp = tmps[i]
        if long_str:sub(index, index + string.len(tmp) - 1) == tmp then
            index = index + string.len(tmp)
            break
        end
    end
    if old_index == index then
        is_none = true
        break
    end
end
print(is_none and "NO" or "YES")