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 C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>
using namespace std;
 
int main(){
    string str;
    cin >> str;
    reverse(str.begin(),str.end());
    cout << str << endl;
    for(int i=0;i<str.length();){
        if(str.substr(i,5) == "maerd" || str.substr(i,5) == "esare"){
            i += 5;
        }else if(str.substr(i,3) == "rem"){
            string s = str.substr(i,min(7,(int)str.length()-i));
            i += 7;
        }else if(str.substr(i,3) == "res"){
            string s = str.substr(i,min(6,(int)str.length()-i));
            i += 6;
        }else{
            cout << "NO" << endl;
            return 0;
        }
    }
    cout << "YES" << endl;
    return 0;
}