#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <algorithm>
#include <fstream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <string>
#include <ctime>
#include <queue>
#include <stack>
#include <vector>
#include <map>
#include <set>
#include <deque>
#include <cassert>

#define pb push_back
#define pp pop_back
#define f first
#define s second
#define mp make_pair
#define sz(a) int((a).size())
#ifdef _WIN32
#  define I64 "%I64d"
#else
#  define I64 "%lld"
#endif
#define fname "."
#define pi pair < int, int >

typedef long long ll;
typedef unsigned long long ull;

const int MAX_N = (int)5e5 + 123;
const int inf = (int)1e9 + 123;

using namespace std;

int n, k;
int a[MAX_N];

int used[(1 << 23)];
ll res[(1 << 23)];

ll dp[MAX_N];

ll solve(int mask) {
	if (used[mask] == 2)
		return res[mask];
	ll &ans = res[mask];
	used[mask] = 1;
	if (!mask) {
		used[mask] = 2;
		return ans = 0;
	}
	ans = (ll)1e18 + 123;
	for (int i = 0; i < n; i++) {
		int nwmask = mask;
		for (int j = max(0, i - k); j <= min(n - 1, i + k); j++)
			nwmask ^= (1 << j);
		if (used[nwmask] != 1)
			ans = min(ans, solve(nwmask) + a[i]);
	}
	used[mask] = 2;
	return ans;
}

int main() {
	#ifdef Nick
	freopen(fname"in","r",stdin);
	freopen(fname"out","w",stdout);
	#endif
	scanf("%d%d", &n, &k);
	for (int i = 0; i < n; i++)
		scanf("%d", &a[i]);
	if (n > 20) {
		for (int i = n; i > 0; i--)
			a[i] = a[i - 1];
	for (int i = 1; i <= n; i++) {
		dp[i] = (ll)1e18;
		if (i - k <= 1)
			dp[i] = a[i];
		else {
			for (int j = i - 1; j >= max(1, i - 2 * k - 1); j--)
				dp[i] = min(dp[i], dp[j] + a[i]);
		}
	}
	ll res = (ll)1e18 + 123;
	for (int i = max(1, n - k); i <= n; i++)
		res = min(res, dp[i]);
	cout << res;
	return 0;
	}
	cout << solve((1 << n) - 1);
	return 0;
}