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 Go (1.6) (judge verdict: Wrong Answer)

package main

import (
	"bufio"
	"fmt"
	"os"
	"strings"
)

var (
	stdin = bufio.NewScanner(os.Stdin)
	t     = []string{"dream", "dreamer", "erase", "eraser"}
)

func main() {
	stdin.Scan()
	s := stdin.Text()
	s = strings.Replace(s, t[0], "D", -1)
	s = strings.Replace(s, t[2], "E", -1)
	s = strings.Replace(s, "Der", "", -1)
	s = strings.Replace(s, "Er", "", -1)
	s = strings.Replace(s, "D", "", -1)
	s = strings.Replace(s, "E", "", -1)
	var o = "NO"
	if s == "" {
		o = "YES"
	}
	fmt.Println(o)
}