Problem: The heat during the last few days has been really intense. Scientists from all over the Berland study how the temperatures and weather change, and they claim that this summer is abnormally hot. But any scientific claim sounds a lot more reasonable if there are some numbers involved, so they have decided to actually calculate some value which would represent how high the temperatures are.

Mathematicians of Berland State University came up with a special heat intensity value. This value is calculated as follows:

Suppose we want to analyze the segment of n consecutive days. We have measured the temperatures during these n days; the temperature during i-th day equals a_i.

We denote the average temperature of a segment of some consecutive days as the arithmetic mean of the temperature measures during this segment of days. So, if we want to analyze the average temperature from day x to day y, we calculate it as \frac{∑ _{i = x}^{y} a_i}{y - x + 1} (note that division is performed without any rounding). The heat intensity value is the maximum of average temperatures over all segments of not less than k consecutive days. For example, if analyzing the measures [3, 4, 1, 2] and k = 3, we are interested in segments [3, 4, 1], [4, 1, 2] and [3, 4, 1, 2] (we want to find the maximum value of average temperature over these segments).

You have been hired by Berland State University to write a program that would compute the heat intensity value of a given period of days. Are you up to this task?

Input

The first line contains two integers n and k (1 ≤ k ≤ n ≤ 5000) — the number of days in the given period, and the minimum number of days in a segment we consider when calculating heat intensity value, respectively.

The second line contains n integers a_1, a_2, ..., a_n (1 ≤ a_i ≤ 5000) — the temperature measures during given n days.

Output

Print one real number — the heat intensity value, i. e., the maximum of average temperatures over all segments of not less than k consecutive days.

Your answer will be considered correct if the following condition holds: |res - res_0| < 10^{-6}, where res is your answer, and res_0 is the answer given by the jury's solution.

Example

Input

4 3
3 4 1 2


Output

2.666666666666667

Solution (in PYTHON):

Solution:
"""
________        _____________              ______
___  __ \____  ____  __ \__(_)__   _______ ___  /
__  /_/ /_  / / /_  /_/ /_  /__ | / /  __ `/_  /
_  ____/_  /_/ /_  _, _/_  / __ |/ // /_/ /_  /
/_/     _\__, / /_/ |_| /_/  _____/ \__,_/ /_/
        /____/

https://github.com/Cheran-Senthil/PyRival
Copyright (c) 2018 Cheran Senthilkumar
"""
from __future__ import division, print_function

import cmath
import itertools
import math
import operator as op
import sys
from atexit import register
from bisect import bisect_left, bisect_right

# import random
# from collections import Counter, MutableSequence, defaultdict, deque
# from copy import deepcopy
# from decimal import Decimal
# from difflib import SequenceMatcher
# from heapq import heappop, heappush

if sys.version_info[0] < 3:
    from io import BytesIO as stream
    # from fractions import Fraction
    # from fractions import gcd
    # from cPickle import dumps
    # from Queue import PriorityQueue, Queue
else:
    from io import StringIO as stream
    # from functools import reduce
    # from fractions import Fraction
    # from math import gcd
    # from pickle import dumps
    # from queue import PriorityQueue, Queue


if sys.version_info[0] < 3:
    class dict(dict):
        def items(self):
            return dict.iteritems(self)

        def keys(self):
            return dict.iterkeys(self)

        def values(self):
            return dict.itervalues(self)

    input = raw_input
    range = xrange

    filter = itertools.ifilter
    map = itertools.imap
    zip = itertools.izip


def sync_with_stdio(sync=True):
    """
    Sets whether the standard Python streams are allowed to buffer their I/O.

    Parameters
    ----------
    sync : bool, optional
        The new synchronization setting. Default is True.
    """
    global input, flush

    if sync:
        flush = sys.stdout.flush
    else:
        sys.stdin = stream(sys.stdin.read())
        input = lambda: sys.stdin.readline().rstrip('\r\n')

        sys.stdout = stream()
        register(lambda: sys.__stdout__.write(sys.stdout.getvalue()))


def main():
    n, k = map(int, input().split(' '))
    a = list(map(int, input().split(' ')))
    partial_sums = [[0] * n for _ in range(n)]
    heat_intensity = 0
    for i in range(len(a)):
        for j in range(i, len(a)):
            if j == i:
                partial_sums[i][j] = a[i]
            else:
                partial_sums[i][j] = partial_sums[i][j - 1] + a[j]
            if 1 + j - i >= k:
                heat_intensity = max(heat_intensity, partial_sums[i][j] / (1 + j - i))
    print(heat_intensity)


if __name__ == '__main__':
    sys.setrecursionlimit(10000)
    sync_with_stdio(False)
    main()