#include<bits/stdc++.h>
using namespace std;

#define F first
#define S second
#define pb push_back
#define mp make_pair
#define var(X) cerr << " --> " << #X << " = " << X << endl
#define arr(a,n) for(int i=0;i<n;i++){if(i==0) cout<<"Results for array "<< #a <<"\n";cout<<a[i]<<" ";} cout<<endl
#define arr1(a,n) for(int i=1;i<=n;i++){if(i==1) cout<<"Results for array "<< #a <<"\n";cout<<a[i]<<" ";} cout<<endl

//setbase - cout << setbase (16); cout << 100 << endl; Prints 64
//setfill -   cout << setfill ('x') << setw (5); cout << 77 << endl; prints xxx77
//setprecision - cout << setprecision (4) << f << endl; Prints x.xxxx

typedef long long ll;
typedef vector<int> vi;
typedef pair<int,int> ii;
typedef vector<pair<int,int> > vii;
const double eps = 1e-10, pi = acos(-1.0);

ll dp[10004],a[10005];


int main()
{
	/*
	#ifndef ONLINE_JUDGE
	freopen("input.txt","r",stdin);
	freopen("out.txt","w",stdout);
	#endif
	*/
	
	int t=1,cs=1;
	//ios_base::sync_with_stdio(0); cin.tie(0);	
	//clock_t start=clock();
	//scanf("%d",&t);
	while(t--)
	{
		int n,k,x,y;
		cin>>n>>k;
		for(int i=1;i<=n;i++)
		{
			cin>>a[i];
			dp[i]=LLONG_MAX;
		}
		dp[0]=0;
		for(int i=1;i<=n;i++)
		{
			dp[i]=min(dp[i],a[i]+dp[max(0,i-k-1)]);
			for(int j=1;j<=k;j++)
			dp[i+j]=min(dp[i+j],a[i]+dp[max(0,i-k-1)]);
		}
		/*for(int i=1;i<=n;i++)
		cout<<dp[i]<<" ";
		cout<<endl;*/
		cout<<dp[n]<<"\n";
		
	}
	//clock_t end=clock();
	//cout <<"Time: " <<(double)(end-start)/CLOCKS_PER_SEC <<" seconds" <<endl;
	return 0;
}