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: Runtime Error)

package main

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

var sc = bufio.NewScanner(os.Stdin)

func scanStr() string {
	sc.Scan()
	return sc.Text()
}

func main() {
	s := scanStr()
	var n string
	n = strings.Replace(s, "drea", ",drea", -1)
	n = strings.Replace(n, "eras", ",eras", -1)

	if n[0:1] == "," {
		n = strings.TrimLeft(n, ",")
	}
	/*
		if n[len(n)-1:len(n)] == "," {
			n = strings.TrimRight(n, ",")
		}
	*/

	l := strings.Split(n, ",")
	fmt.Println(l)

	ok := true
	for _, i := range l {
		if i == "eraser" || i == "erase" || i == "dream" || i == "dreamer" {
			continue
		} else {
			ok = false
			break
		}
	}

	if ok {
		fmt.Println("YES")
	} else {
		fmt.Println("NO")
	}
}