#include <bits/stdc++.h>
#include <math.h>

using namespace std;

int vals[100000];
int memo[100000];

int solve(int k, int n, int vals[])
{
        int ans;

        if(n<0)
            return 0;
        else if(memo[n] == -1)
        {
            ans = vals[n] + solve(k, n-k-1, vals);
            for(int i = 1; i<=k; i++)
               ans = max(ans, solve(k, n-i, vals));
            memo[n] = ans;
        }

        return memo[n];
}

int main() {
    int n, k;
    cin >> n >> k;
    for(int i = 0; i < n; i++)
        cin >> vals[i];
    for(int j = 0; j < n; j++)
        memo[j] = -1;
    // solve and print answer here
    printf("%d", solve(k, n-1, vals));
}