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 Fortran (gfortran v4.8.4) (judge verdict: Accepted)

program main
   character(len=7) :: s(4) = (/"dream  ", "dreamer", "erase  ", "eraser "/)
   character(len=100000) :: b
   integer :: L(4) = (/5, 7, 5, 6/)
   read(*, *) b
   N = len_trim(b)
   a: do while(N > 0)
      do i = 1, 4
         if(N < L(i)) cycle
         if(trim(s(i)) == b(N-L(i)+1:N))then
            N = N - L(i)
            cycle a
         endif
      enddo
      write(*, *)"NO"
      stop
   enddo a
   write(*, *) "YES"
end