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<iostream>
#include<iomanip>
#include<map>
#include<unordered_map>
#include<set>
#include<unordered_set>
#include<vector>
#include<array>
#include<string>
#include<stack>
#include<queue>
#include<algorithm>
#include<cassert>
#include<functional>
#include<random>
#include<complex>
#include<bitset>
#include<chrono>
//#include<boost/multiprecision/cpp_int.hpp>
#define int int64_t
#define uint uint64_t
#define REP(i, a, b) for (int64_t i = (int64_t)(a); i < (int64_t)(b); i++)
#define rep(i, a) REP(i, 0, a)
#define EACH(i, a) for (auto i: a)
#define ITR(x, a) for (auto x = a.begin(); x != a.end(); x++)
#define ALL(a) (a.begin()), (a.end())
#define HAS(a, x) (a.find(x) != a.end())
#define Min(x) *min_element(ALL(x))
#define Max(x) *max_element(ALL(x))
#define Unique(L) (L.erase(unique(ALL(L)), L.end()))
#define intmax (std::numeric_limits<int64_t>::max() / 4)
#define doublemax (std::numeric_limits<double>::max() / 4)
using namespace std;
//typedef boost::multiprecision::cpp_int bigint;
const double EPS = 1e-9;
const double PI = acos(-1.0);



signed main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	
	string S;
	cin >> S;
	vector<string> a= { "dreamer","dream","eraser","erase" };
	int cursor = 0;
	while (cursor < S.size()) {
		bool ff = false;
		rep(i, a.size())if (cursor + a[i].size() <= S.size()) {
			bool flag = true;
			rep(j, a[i].size())if (a[i][j] != S[cursor + j]) { flag = false; break; }
			if (flag == true) {
				ff = true;
				cursor += a[i].size();
				break;
			}
		}
		if (ff == false) {
			cout << "NO" << endl;
			return 0;
		}
	}
	cout << "YES" << endl;
	return 0;
}