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 Common Lisp (SBCL 1.1.14) (judge verdict: Runtime Error)

(loop :named n-loop :with n := (read)
      :do (loop :for j :upto n :with y := (read)
                :do (loop :for k :upto (- n j)
                          :if (= y (+ (* 10000 j) (* 5000 k) (* 1000 (- n j k))))
                            :do (format t "~A ~A ~A" j k (- n j k))
                            :and
                              :do (return-from n-loop))
                :finally (princ "-1 -1 -1")))