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: Accepted)

const a:array[0..3]of string=('eraser','erase','dreamer','dream');
var s:ansistring;
    i,t,x:longint;
begin
  readln(s);
  for i:=0 to 3 do
  begin
    t:=pos(a[i],s);
    x:=length(a[i]);
    while t<>0 do
    begin
      delete(s,t,x);
      t:=pos(a[i],s);
    end;
  end;
  if length(s)<>0 then
    writeln('NO')
  else
    writeln('YES');
end.