Maximum Sum of K Consecutive Elements

Given an array of n integers, your task is to find the maximum sum of any subarray containing exactly k consecutive elements. Formally, if the array is \(a = [a_0, a_1, \dots, a_{n-1}]\), you need to compute:

\(\max_{0 \le i \le n-k} \sum_{j=i}^{i+k-1} a_j\)

This problem can be solved efficiently using a sliding window technique. Note that the array may contain negative numbers, so make sure to handle all edge cases.

inputFormat

The first line of input contains two space-separated integers: n (the number of elements in the array) and k (the number of consecutive elements to consider). The second line contains n space-separated integers representing the elements of the array.

outputFormat

Output a single integer representing the maximum sum of any subarray of exactly k consecutive elements.

## sample

5 2
1 2 3 4 5

9

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