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 test
implicit none
integer::l
character::S*100000
read(*,*)S
l=len_trim(S)
do 
	if(l==0)then
    print*,'YES'
    stop
	else if(S(l-4:l)=='dream')then
    	l=l-5
   	else if(S(l-6:l)=='dreamer')then
    	l=l-7
    else if(S(l-4:l)=='erase')then
    	l=l-5
    else if(S(l-5:l)=='eraser')then
    	l=l-6
    else 
    	print*,'NO'
        stop
    end if
end do
end program test