#include<bits/stdc++.h>
#define INF 1000000007
using namespace std;
int dp[505][505];
int a[100005];
int n, m;
int main()
{
	freopen("cowrun.in","r",stdin);
    freopen("cowrun.out","w",stdout);
    scanf("%d%d", &n, &m);
    for(int i = 1; i <= n; i++) 
	scanf("%d", &a[i]);
    for(int i = 1; i <= n; i++)
    {
        dp[i][0] = dp[i - 1][0];
        for(int j = 1; j <= m; j++)
        {
            if(i>=j)
			dp[i][0]=max(dp[i][0], dp[i - j][j]);
            dp[i][j]=max(dp[i-1][j-1]+a[i],dp[i][j]);
        }
    }
    printf("%d\n", dp[n][0]);
    return 0;
}