#include <cstdio>
#include <algorithm>
#define LL long long
using namespace std;
const int N = 1e5 + 5;
LL n, k, a[N], sum[N], f[N];
int main() {
	scanf("%lld%lld", &n, &k);
	for (LL i = 1; i <= n; i ++ ) {
		scanf("%lld", &a[i]);
  		sum[i] = a[i] + sum[i - 1];
	}
	for (int i = 1; i <= n + 1; i ++ )
		for (int j = max(1LL * 0, i - k - 1); j < i; j ++ )
			f[i] = max(f[i], f[j] + sum[i - 1] - sum[j]);
	printf("%lld\n", f[n + 1]);
	return 0;
}