2559번

2559

#include <iostream>
#include <vector>
using namespace std;

int main() {
	int n, k;
	cin >> n >> k;
	vector<int> v;

	for (int i = 0; i < n; i++) {
		int input;
		cin >> input;
		v.push_back(input);
	}

	int sum = 0;
	int index = 0;
	for (int i = 0; i < k; i++) {
		sum += v[i];
	}
	int result = sum;

	while (index < n) {
		int copySum = sum;
		if (index + k < n) {
			copySum -= v[index];
			copySum += v[index + k];
		}
		index++;
		sum = copySum;
		result = max(result, copySum);
	}
	cout << result;
}