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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <string.h>
int main() {
	int i;
	char s[100010];
	scanf("%s", s);
	i = strlen(s) - 1;
	while (i >= 0)
	{
		if (s[i - 4] == 'd' && s[i - 3] == 'r' && s[i - 2] == 'e' && s[i - 1] == 'a' && s[i] == 'm') {
			i -= 5;
		}
		if (s[i - 6] == 'd' && s[i - 5] == 'r' && s[i - 4] == 'e' && s[i -3] == 'a' && s[i- 2] == 'm' && s[i - 1] == 'e' && s[i] == 'r') {
			i -= 7;
		}
		else if (s[i - 4] == 'e' && s[i - 3] == 'r' && s[i - 2] == 'a' && s[i - 1] == 's' && s[i] == 'e') {
			i -= 5;
		}
		else if(s[i - 5] == 'e' && s[i - 4] == 'r' && s[i - 3] == 'a' && s[i - 2] == 's' && s[i - 1] == 'e' && s[i] == 'r'){
			i -= 6;
		}
		else
		{
			printf("NO\n");
			return 0;
		}
	}
	printf("YES\n");
	return 0;
}