#include <bits/stdc++.h>

using namespace std;

#define FOR(i,a,b) for(int i = (a); i <= (b); ++i)
#define FORD(i,a,b) for(int i = (a); i >= (b); --i)
#define RI(i,n) FOR(i,1,(n))
#define REP(i,n) FOR(i,0,(n)-1)
#define mini(a,b) a=min(a,b)
#define maxi(a,b) a=max(a,b)
#define mp make_pair
#define pb push_back
#define st first
#define nd second
#define sz(w) (int) w.size()
typedef vector<int> vi;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
const int inf = 1e9 + 7;
const ll infi = 1e18 + 7;
const int maxN = 1e6 + 5;

int n, k;
int arr[maxN];
ll dp[10005][1009];
deque<ll> Q[1009];

int main() {
	scanf("%d%d",&n,&k);
	RI(i, n) {
		dp[i][0] = infi;
		scanf("%d",&arr[i]);
		RI(j, k)
			dp[i][j] = infi;
	}
	RI(j, k)
		Q[j].push_back(infi);
	RI(i, n) {
		RI(j, k) {
			//printf("Dla %d %d : ",i, j);
			ll x = Q[j].front();
			//printf("%lld %lld\n", x, dp[max(i - k - 1, 0)][j - 1] + arr[i]);
			dp[i][j] = min(x, dp[max(i - k - 1, 0)][j - 1] + arr[i]);
			while (!Q[j].empty() && dp[i][j] <= Q[j].back()) {
				Q[j].pop_back();
			}
			Q[j].push_back(dp[i][j]);
		}
	}
	ll ans = infi;
	RI(j, k) {
		mini(ans, dp[n][j]);
	}
	printf("%lld",ans);
	return 0;
}