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 Pascal (FPC 2.6.2) (judge verdict: Wrong Answer)

var
  s:ansistring;
  l:longint;
begin
  readln(s);
  if length(s)<5 then begin writeln('NO');exit;end;
  l:=length(s);
  if (s[l]='m') and (s[l-1]='a') and (s[l-2]='e') and (s[l-3]='r') and (s[l-4]='d') then begin writeln('YES');exit;end;
  if (s[l]='r') and (s[l-1]='e') and (s[l-2]='m') and (s[l-3]='a') and (s[l-4]='e') and (s[l-5]='r') and (s[l-6]='d') then begin writeln('YES');exit;end;
  if (s[l]='e') and (s[l-1]='s') and (s[l-2]='a') and (s[l-3]='r') and (s[l-4]='e') then begin writeln('YES');exit;end;
  if (s[l]='r') and (s[l-1]='e') and (s[l-2]='s') and (s[l-3]='a') and (s[l-4]='r') and (s[l-5]='e') then begin writeln('YES');exit;end;
  writeln('NO');
end.