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 tenquestionnine
 implicit none
 character(10**5) :: S
 character(7) :: T(4) = (/"dream  ","dreamer","erase  ","eraser "/)
 integer :: L(4) = (/5,7,5,6/)
 integer i, len
 read(*,*) S
 len=len_trim(S)
 a: do while (len.gt.0)
  do i=1,4
   if((trim(T(i))).eq.(S((len-L(i)+1):len))) then
   len = len - L(i)
   cycle a
   end if
  end do
  write(*,*) "NO"
  return
  end do a
  write(*,*) "YES"
end program