Maximum Sum Subarray of Fixed Length

You are given an array of n non-negative integers, and a positive integer k. Your task is to find a contiguous subarray of length exactly k that has the maximum sum among all possible subarrays of this length.

In mathematical terms, if the array is represented as \(A = [a_0, a_1, \dots, a_{n-1}]\), you need to compute:

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

If n or k is zero, the result should be 0.

inputFormat

The input is provided via stdin and consists of:

• The first line contains two space-separated integers n and k — the number of elements in the array and the length of the subarray respectively.
• The second line contains n space-separated non-negative integers representing the array.

outputFormat

The output should be written to stdout and consists of a single integer — the maximum sum of any contiguous subarray of length k. If n or k is zero, output 0.

6 3
1 2 3 4 5 6

15