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: Accepted)

// ABC 049 C - Daydream
package main

import (
    "fmt"
    "strings"
)

func main() {

    var s string
    fmt.Scan(&s)

    s = reverse(s)
    s = strings.Replace(s, "resare", "", -1)
    s = strings.Replace(s, "esare", "", -1)
    s = strings.Replace(s, "remaerd", "", -1)
    s = strings.Replace(s, "maerd", "", -1)

    var res string
    if len(s) == 0 {
        res = "YES"
    } else {
        res = "NO"
    }
    fmt.Println(res)
}

func reverse(s string) string {
    bs := []byte(s)
    for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 {
        bs[i], bs[j] = bs[j], bs[i]
    }
    return string(bs)
}