====== 수열 ======

===== 풀이 =====
  * [[ps:투 포인터#슬라이딩 윈도우]] 기법의 가장 기본적인 형태. 시간복잡도는 O(N)

===== 코드 =====
<dkpr py>
"""Solution code for "BOJ 2559. 수열".

- Problem link: https://www.acmicpc.net/problem/2559
- Solution link: http://www.teferi.net/ps/problems/boj/2559

Tags: [Sliding window]
"""


def main():
    N, K = [int(x) for x in input().split()]  # pylint: disable=unused-variable
    nums = [int(x) for x in input().split()]

    answer = s = sum(nums[:K])
    for l, r in zip(nums, nums[K:]):
        s += r - l
        answer = max(answer, s)

    print(answer)


if __name__ == '__main__':
    main()
</dkpr>

{{tag>BOJ ps:problems:boj:실버_4}}