#include<iostream>
#include<string>
#include<cctype>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<vector>
#include<algorithm>
#include<map>
#include<set>
#include<iomanip>
using namespace std;
#define int long long
const int N = 2e5+10;
const int INF = 0x3f3f3f3f3f3f3f3f;
int n,m,a[N],dp[N],q[N],num[N],sum=0;
signed main(){
	//freopen("","r",stdin);
	//freopen("","w",stdout);
	cin>>n>>m;
	m++;
	for(int i=1;i<=n;i++){
		cin>>a[i];
		sum+=a[i];
	}
	int l,r;
	l=r=1,q[r++]=0;
	for(int i=1;i<=n;i++){
		while(l<r&&q[l]<=i-m-1)l++;
		dp[i]=a[i]+num[l];
		while(l<r&&num[r-1]>dp[i])r--;
		num[r]=dp[i];
		q[r++]=i;
	}
	int minn=INF;
	for(int i=n;i>n-m;i--)minn=min(minn,dp[i]);
	cout<<sum-minn<<endl;
	return 0;
}