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 Perl (v5.18.2) (judge verdict: Accepted)

use strict;
use warnings;

my $buf = <>;
chomp $buf;

$buf =~ s/eraser//g;
$buf =~ s/erase//g;
$buf =~ s/dreamer//g;
$buf =~ s/dream//g;
if($buf eq ""){
	print "YES\n";
}else{
	print "NO\n";
}