//It’s never too late to become what you might have been....
 #include <iostream>
#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define inf 1000000000000000
#define mod 1000000007
#define pb push_back
#define mp make_pair
#define all(v) v.begin(),v.end()
#define S second
#define F first
#define boost1 ios::sync_with_stdio(false);
#define boost2 cin.tie(0);
#define mem(a,val) memset(a,val,sizeof a)
#define endl "\n"
#define maxn 100001

ll a[maxn],dp[maxn],tree[4*maxn];

void update(ll node,ll a,ll b,ll ind,ll val)
{
	if(a>b || a>ind || b<ind)
	return ;
	if(a==b)
	{
		tree[node]=val;
		return;
	}	
	ll mid=(a+b)/2;
	if(ind<=mid)
	update(2*node,a,mid,ind,val);
	else
	update(2*node+1,mid+1,b,ind,val);
	tree[node]=min(tree[2*node],tree[2*node+1]);
}
ll query(ll node,ll a,ll b,ll l,ll r)
{
	if(a>b || a>r || b<l)
	return inf;
	if(a>=l && b<=r)
	return tree[node];
	ll mid=(a+b)/2;
	return min(query(2*node,a,mid,l,r),query(2*node+1,mid+1,b,l,r));
}
int main()
{
	boost1;boost2;
	ll i,j,n,k,x,y;
	cin>>n>>k;
	for(i=0;i<4*maxn;i++)
	tree[i]=inf;
	for(i=1;i<=n;i++)
	cin>>a[i];
	for(i=0;i<=n;i++)
	dp[i]=inf;
	dp[0]=0;
	update(1,0,n,0,dp[0]);
	dp[1]=a[1];
	update(1,0,n,1,dp[1]);
	for(i=2;i<=n;i++)
	{
		for(j=max(1LL,i-k);j<=i;j++)
		dp[i]=min(dp[i],a[j]+query(1,0,n,max(0LL,j-k-1),j-1));
		update(1,0,n,i,dp[i]);
	}	
	//cout<<dp[2]<<endl;
	cout<<dp[n];
	return 0;
}