#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>

using namespace std;  
int dp[10001][501];  
int a[10001]; 
int n, m;  
int max(int a,int b)
{
	return a>b? a:b;
}
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]);  
    fclose(stdin);fclose(stdout);
    return 0;  
}