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 Kotlin (1.0.0) (judge verdict: Wrong Answer)

fun main(args: Array<String>) {
    val additionForT = listOf("dream", "dreamer", "erase", "eraser")

    val s = readLine()!!

    val flag = checkCanSame(s, additionForT)

    if (flag) {
        println("YES")
    } else {
        println("NO")
    }
}

fun checkCanSame(s: String, additionForT: List<String>): Boolean {
    for (add1 in additionForT) {
        for (add2 in additionForT) {
            if (s.endsWith(add1)) {
                val subS = s.substring(0, s.length - add1.length)
                println(subS)
                if (subS.endsWith(add2)) {
                    return true
                }
            }
        }
    }
    return false
}