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: Wrong Answer)

character(10**5) S
character(5)::dream="dream"
character(7)::dreamer="dreamer"
character(5)::erase="erase"
character(6)::eraser="eraser"
integer start
logical check
read*,S
start=1
check=.TRUE.
do
  if(S(start:start+6)==dreamer)then
    start=start+7
  else if(S(start:start+4)==dream)then
    start=start+5
  else if(S(start:start+5)==eraser)then
    start=start+6
  else if(S(start:start+4)==erase)then
    start=start+5
  else
    check=.false.
    exit
  endif
  if(start==len_trim(S)+1)exit
end do
print"(A)",trim(merge("YES","NO ",check))
end