#include<cstdio>
#include<algorithm>
#define COGS
using namespace std;
const int maxn=10010;
int n,m,d[maxn],temp;
int f[maxn];
inline void in(){
	#ifdef COGS
	freopen("cowrun.in","r",stdin);
	freopen("cowrun.out","w",stdout);
	#endif
	scanf("%d%d",&n,&m);
	for (int i=1;i<=n;i++){
		scanf("%d",&temp);
		d[i]+=d[i-1]+temp;
	}
}
inline void deal(){
	for (int i=1;i<=n;i++){
		f[i]=f[i-1];
		for (int j=1;2*j<=i&&j<=m;j++){
			f[i]=max(f[i],f[i-2*j]+d[i-j]-d[i-2*j]);
		}
	}
}
inline void p(){
	printf("%d",f[n]);
}
int Main(){
	in();
	deal();
	p();
	return 0;
}
int main(){;}
int xlm=Main();