#include<bits/stdc++.h>
using namespace std;
int f[10002];
int i,j,n,m;
int a[10002];
int s[10002];
int main()
{
	freopen("cowrun.in","r",stdin);
	freopen("cowrun.out","w",stdout);
	scanf("%d%d",&n,&m);
	for (i=1;i<=n;i++){
		scanf("%d",&a[i]);
		s[i]=s[i-1]+a[i];
	}
	for (i=1;i<=n;i++){
		f[i]=f[i-1];
        for (int j=1;j<=m&&j+j<=i;j++)
            if (f[i-2*j]+s[i-j]-s[i-2*j]>f[i]) 
                f[i]=f[i-2*j]+s[i-j]-s[i-2*j];
    }
	printf("%d",f[n]);
	return 0;
}