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
   implicit none
   character(100000) s,st
   integer le,i
   read(*,*)st
   le=len_trim(st)
   do i=1,le
      s(i:i)=st(le-i+1:le-i+1)
   enddo
   i=1
   do
    !  write(*,*)i
      if(i==le+1)then
         write(*,"(A3)")"YES"
         STOP
      endif
      if(s(i:i+4)=="maerd")then
      i=i+5
      cycle;
     endif
      if(s(i:i+6)=="remaerd")then
      i=i+7
      cycle;
     endif
     if(s(i:i+4)=="esare")then
      i=i+5
      cycle;
     endif
      if(s(i:i+5)=="resare")then
      i=i+6
      cycle;
     endif
     write(*,"(A2)")"NO"
     STOP
      
   enddo
end program main