#include <bits/stdc++.h>

using namespace std;


#define si(i)                   scanf("%d",&i)
#define si2(i,j)                scanf("%d %d",&i,&j)
#define si3(i,j,k)              scanf("%d %d %d",&i,&j,&k)
#define slli(i)                 scanf("%lld",&i)
#define slli2(i,j)              scanf("%lld %lld",&i,&j)
#define slli3(i,j,k)            scanf("%lld %lld %lld",&i,&j,&k)

#define pi(i)                   printf("%d\n",i)
#define plli(i)                 printf("%lld\n",i)

#define SYNC                    ios_base::sync_with_stdio(0)
#define mp                      make_pair
#define FF                      first
#define SS                      second
#define pb                      push_back
#define fill(a,v)               memset(a,v,sizeof a)
#define ceil(a,b)               (((a)%(b)==0)?((a)/(b)):((a)/(b)+1))
#define rem(a,b)                ((a<0)?((((a)%(b))+(b))%(b)):((a)%(b)))
#define MOD                     1000000007LL
#define INF                     10000000000000000LL
#define N                       100007


typedef long long int ll;
typedef pair<int,int> PII;
typedef pair<ll,ll> PLL;
typedef vector<string> VS;
typedef vector<int> VI;
typedef vector<ll> VL;
typedef vector<PII> VOII;
typedef vector<PLL> VOLL;
typedef vector<VI> VOVI;

int dX[] = {-1,0,1,0,-1,1,1,-1};
int dY[] = {0,1,0,-1,1,1,-1,-1};




ll n,k;
ll c[10005];

map<pair<PLL,PLL>,ll> data;


ll recurse(ll l,ll r,ll lft,ll ryt) {
	if(l > r) return 0;
	if(data.find(mp(mp(l,r),mp(lft,ryt))) != data.end()) return data[mp(mp(l,r),mp(lft,ryt))]; 
	ll ret = INF;
	if(lft == 1 && ryt == 1) {
		for (ll i = l; i <= l + k && i <= r; ++i) {
			ret = min(ret,c[i] + recurse(i + k + 1,r,0,1));
		}
		for (ll i = r; i >= r - k && i >= l; --i) {
			ret = min(ret,c[i] + recurse(l,i - k - 1,1,0));
		}
	}
	else if(lft == 0 && ryt == 0) {
		if(r - l + 1 < 2*k + 1) return ret;
		ret = min(ret,c[l + k] + recurse(l + 2*k + 1,r,0,0));
		ret = min(ret,c[r - k] + recurse(l,r - 2*k - 1,0,0));
	}
	else if(lft == 0 && ryt == 1) {
		for (ll i = r; i >= r - k && i - k >= l; --i) {
			ret = min(ret,c[i] + recurse(l,i - k - 1,0,0));
		}
		if(l + 2*k <= r) ret = min(ret,c[l + k] + recurse(l + 2*k + 1,r,0,1));
	}
	else {
		for (ll i = l; i <= l + k && i + k <= r; ++i) {
			ret = min(ret,c[i] + recurse(i + k + 1,r,0,0));
		}
		if(r - 2*k >= l) ret = min(ret,c[r - k] + recurse(l,r - 2*k - 1,1,0));
	}
	data[mp(mp(l,r),mp(lft,ryt))] = ret;
	return ret;
}


int main()
{
    cin >> n >> k;
    for (ll i = 1; i <= n; ++i) {
    	cin >> c[i];
    }
    cout << recurse(1,n,1,1) << endl;
    return 0;
}