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
  n:string;
 function pd(n:string):boolean;
  var
    l:longint;
  begin
    l:=length(n);
    if(n[l]='m')and(n[l-1]='a')and(n[l-2]='e')and(n[l-3]='r')and(n[l-4]='d')then exit(true);
    if(n[l]='r')and(n[l-1]='e')and(n[l-2]='m')and(n[l-3]='a')and(n[l-4]='e')and(n[l-5]='r')and(n[l-6]='d')then exit(true);
    if(n[l]='e')and(n[l-1]='s')and(n[l-2]='a')and(n[l-3]='r')and(n[l-4]='e')then exit(true);
    if(n[l]='r')and(n[l-1]='e')and(n[l-2]='s')and(n[l-3]='a')and(n[l-4]='r')and(n[l-5]='e')then exit(true);
    exit(false);
  end;
begin
  readln(n);
  if pd(n) then writeln('YES') else writeln('NO');
end.