#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;

#define forr(_a, _b, _c) for(_a = (_b); _a <= (_c); ++_a)
#define ford(_a, _b, _c) for(_a = (_b) + 1; _a --> (_c);)
#define forf(_a, _b, _c) for(_a = (_b); _a < (_c); ++_a)
#define mp make_pair
#define fi first
#define se second
#define vi vector
#define sz(_v) _v.begin(), _v.end()
#define mask(_x) (1ll << (_x))
#define bit(_x,_y) (((_x) >> (_y)) & 1)

string yes[2] = {"NO\n","YES\n"};
const ld eps = ld(1e-7);
const ll inf = ll(1e16) + 1;
const ll mod = ll(1e9) + 7;

const int N = 2e5 + 5;
ll n, i, a[N], t, f[N], o = inf, k;

void solve() {
	cin >> n >> k;
	forr(i,1,n) {
		cin >> a[i];
		t += a[i];
		f[i] = f[max(0ll,i - k)] + a[i];
	}
	forr(i,1,n) {
		o = min(o,t - f[i]);
	}
	cout << o;
}

void precalc() {
}

int main() {
	ios_base::sync_with_stdio(false); cin.tie(NULL);
	#ifdef umf
		freopen("test.inp","r",stdin);
		freopen("test.out","w",stdout);
	#endif

	int tc = 1;
	// cin >> tc;
	precalc();
	while(tc --> 0) {
		solve();
	}

	return 0;
}