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 Fortran (gfortran v4.8.4) (judge verdict: Wrong Answer)

program abc049c
    use,intrinsic :: iso_fortran_env
    implicit none
    character(100000):: s
    character(:),allocatable:: dream, dreamer, erase, eraser
    integer(int32):: i


    dream = 'dream'
    dreamer = 'dreamer'
    erase = 'erase'
    eraser = 'eraser'

    read*, s

    do while(len_trim(s) > 0)

        i = index(s,dream//eraser)
        if (i > 0) then
            s=s(12:)
            cycle
        end if
        i = index(s,dream//erase)
        if (i > 0) then
            s=s(11:)
            cycle
        end if

        i = index(s,dreamer)
        if (i > 0) then
            s = s(8:)
            cycle
        end if

        i = index(s,dream)
        if (i > 0) then
            s = s(6:)
            cycle
        end if

        i = index(s,eraser)
        if (i > 0) then
            s = s(7:)
            cycle
        end if

        i = index(s,erase)
        if (i > 0) then
            s = s(6:)
            cycle
        end if

        print'(a)', 'NO'
        stop
    end do
    print'(a)', 'YES'
end program abc049c