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문제

You are given an array of N integers. Find a consecutive subsequence of numbers of the length at least K that has the maximal possible average.

Please note: the average of a subsequence is the sum of all the numbers in the subsequence divided by its length.

입력

The first line of input contains two integers N (1 ≤ N ≤ 3·105) and K (1 ≤ K ≤ N). The second line of input contains N integers ai (1 ≤ ai ≤ 106).

출력

The first and only line of output must contain the maximal possible average. An absolute deviation of ±0.001 from the official solution is permitted.

예제 입력

4 1
1 2 3 4

예제 출력

4.000000

예제 입력 2

4 2
2 4 3 4

예제 출력 2

3.666666

예제 입력 3

6 3
7 1 2 1 3 6

예제 출력 3

3.333333

힌트