#include<bits/stdc++.h>
using namespace std;
inline void in(int &x){
	x=0;char c=getchar();
	while(!isdigit(c))c=getchar();
	while(isdigit(c))x=(x<<1)+(x<<3)+(c^48),c=getchar();
}
const int N=2e5+10;
unsigned long long f[N],sum[N];
int n,k;
int a[N];

int main(){
	freopen("mowlawn.in","r",stdin);
	freopen("mowlawn.out","w",stdout);
	ios::sync_with_stdio(false);
	in(n);in(k);
	//cin>>n>>k;
	for(int i=1;i<=n;i++)in(a[i]),sum[i]=sum[i-1]+a[i];
	for(int i=1;i<=k;i++)f[i]=sum[i];
	for(int i=0;i<=n;i++){
		for(int j=1;j<=k;j++){
			f[i+1+j]=max(f[i+1+j],f[i]+sum[i+1+j]-sum[i+1]);
		}
	}
	cout<<f[n]<<endl;
	return 0;
}