#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); i++)
#define per(i, n) for (int i = (n)-1; i >= 0; i--)
#define rep2(i, l, r) for (int i = (l); i < (r); i++)
#define per2(i, l, r) for (int i = (r)-1; i >= (l); i--)
#define each(e, v) for (auto &e : v)
#define MM << " " <<
#define pb push_back
#define eb emplace_back
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define sz(x) (int)x.size()
using ll = long long;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;

template <typename T>
using minheap = priority_queue<T, vector<T>, greater<T>>;

template <typename T>
using maxheap = priority_queue<T>;

template <typename T>
bool chmax(T &x, const T &y) {
    return (x < y) ? (x = y, true) : false;
}

template <typename T>
bool chmin(T &x, const T &y) {
    return (x > y) ? (x = y, true) : false;
}

template <typename T>
int flg(T x, int i) {
    return (x >> i) & 1;
}

template <typename T>
void print(const vector<T> &v, T x = 0) {
    int n = v.size();
    for (int i = 0; i < n; i++) cout << v[i] + x << (i == n - 1 ? '\n' : ' ');
    if (v.empty()) cout << '\n';
}

template <typename T>
void printn(const vector<T> &v, T x = 0) {
    int n = v.size();
    for (int i = 0; i < n; i++) cout << v[i] + x << '\n';
}

template <typename T>
int lb(const vector<T> &v, T x) {
    return lower_bound(begin(v), end(v), x) - begin(v);
}

template <typename T>
int ub(const vector<T> &v, T x) {
    return upper_bound(begin(v), end(v), x) - begin(v);
}

template <typename T>
void rearrange(vector<T> &v) {
    sort(begin(v), end(v));
    v.erase(unique(begin(v), end(v)), end(v));
}

template <typename T>
vector<int> id_sort(const vector<T> &v, bool greater = false) {
    int n = v.size();
    vector<int> ret(n);
    iota(begin(ret), end(ret), 0);
    sort(begin(ret), end(ret), [&](int i, int j) { return greater ? v[i] > v[j] : v[i] < v[j]; });
    return ret;
}

template <typename S, typename T>
pair<S, T> operator+(const pair<S, T> &p, const pair<S, T> &q) {
    return make_pair(p.first + q.first, p.second + q.second);
}

template <typename S, typename T>
pair<S, T> operator-(const pair<S, T> &p, const pair<S, T> &q) {
    return make_pair(p.first - q.first, p.second - q.second);
}

template <typename S, typename T>
istream &operator>>(istream &is, pair<S, T> &p) {
    S a;
    T b;
    is >> a >> b;
    p = make_pair(a, b);
    return is;
}

template <typename S, typename T>
ostream &operator<<(ostream &os, const pair<S, T> &p) {
    return os << p.first << ' ' << p.second;
}

struct io_setup {
    io_setup() {
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        cout << fixed << setprecision(15);
    }
} io_setup;

const int inf = (1 << 30) - 1;
const ll INF = (1LL << 60) - 1;
// const int MOD = 1000000007;
const int MOD = 998244353;

template <typename T>
struct Binary_Indexed_Tree {
    vector<T> bit;
    const int n;

    Binary_Indexed_Tree(const vector<T> &v) : n((int)v.size()) {
        bit.resize(n + 1);
        copy(begin(v), end(v), begin(bit) + 1);
        for (int a = 2; a <= n; a <<= 1) {
            for (int b = a; b <= n; b += a) bit[b] += bit[b - a / 2];
        }
    }

    Binary_Indexed_Tree(int n, const T &x) : Binary_Indexed_Tree(vector<T>(n, x)) {}

    void add(int i, const T &x) {
        for (i++; i <= n; i += (i & -i)) bit[i] += x;
    }

    void change(int i, const T &x) { add(i, x - query(i, i + 1)); }

    T sum(int i) const {
        i = min(i, n);
        T ret = 0;
        for (; i > 0; i -= (i & -i)) ret += bit[i];
        return ret;
    }

    T query(int l, int r) const {
        if (l >= r) return 0;
        return sum(r) - sum(l);
    }

    T operator[](int i) const { return query(i, i + 1); }

    // v[0]+...+v[r] >= x を満たす最小の r (なければ n)
    int lower_bound(T x) const {
        int ret = 0;
        for (int k = 31 - __builtin_clz(n); k >= 0; k--) {
            if (ret + (1 << k) <= n && bit[ret + (1 << k)] < x) x -= bit[ret += (1 << k)];
        }
        return ret;
    }

    // v[0]+...+v[r] > x を満たす最小の r (なければ n)
    int upper_bound(T x) const {
        int ret = 0;
        for (int k = 31 - __builtin_clz(n); k >= 0; k--) {
            if (ret + (1 << k) <= n && bit[ret + (1 << k)] <= x) x -= bit[ret += (1 << k)];
        }
        return ret;
    }
};

template <typename Monoid>
struct Segment_Tree {
    using F = function<Monoid(Monoid, Monoid)>;
    int n;
    vector<Monoid> seg;
    const F f;
    const Monoid e1;

    // f(f(a,b),c) = f(a,f(b,c)), f(e1,a) = f(a,e1) = a

    Segment_Tree(const vector<Monoid> &v, const F &f, const Monoid &e1) : f(f), e1(e1) {
        int m = v.size();
        n = 1;
        while (n < m) n <<= 1;
        seg.assign(2 * n, e1);
        copy(begin(v), end(v), seg.begin() + n);
        for (int i = n - 1; i > 0; i--) seg[i] = f(seg[2 * i], seg[2 * i + 1]);
    }

    Segment_Tree(int m, const Monoid &x, const F &f, const Monoid &e1) : Segment_Tree(vector<Monoid>(m, x), f, e1) {}

    void change(int i, const Monoid &x, bool update = true) {
        if (update) {
            seg[i + n] = x;
        } else {
            seg[i + n] = f(seg[i + n], x);
        }
        i += n;
        while (i >>= 1) seg[i] = f(seg[2 * i], seg[2 * i + 1]);
    }

    Monoid query(int l, int r) const {
        l = max(l, 0), r = min(r, n);
        Monoid L = e1, R = e1;
        l += n, r += n;
        while (l < r) {
            if (l & 1) L = f(L, seg[l++]);
            if (r & 1) R = f(seg[--r], R);
            l >>= 1, r >>= 1;
        }
        return f(L, R);
    }

    Monoid operator[](int i) const { return seg[n + i]; }

    template <typename C>
    int find_subtree(int i, const C &check, const Monoid &x, Monoid &M, int type) const {
        while (i < n) {
            Monoid nxt = type ? f(seg[2 * i + type], M) : f(M, seg[2 * i + type]);
            if (check(nxt, x)) {
                i = 2 * i + type;
            } else {
                M = nxt;
                i = 2 * i + (type ^ 1);
            }
        }
        return i - n;
    }

    // check((区間 [l,r] での演算結果), x) を満たす最小の r (存在しなければ n 以上の値)
    template <typename C>
    int find_first(int l, const C &check, const Monoid &x) const {
        Monoid L = e1;
        int a = l + n, b = n + n;
        while (a < b) {
            if (a & 1) {
                Monoid nxt = f(L, seg[a]);
                if (check(nxt, x)) return find_subtree(a, check, x, L, 0);
                L = nxt, a++;
            }
            a >>= 1, b >>= 1;
        }
        return n;
    }

    // check((区間 [l,r) での演算結果), x) を満たす最大の l (存在しなければ -1)
    template <typename C>
    int find_last(int r, const C &check, const Monoid &x) const {
        Monoid R = e1;
        int a = n, b = r + n;
        while (a < b) {
            if ((b & 1) || a == 1) {
                Monoid nxt = f(seg[--b], R);
                if (check(nxt, x)) return find_subtree(b, check, x, R, 1);
                R = nxt;
            }
            a >>= 1, b >>= 1;
        }
        return -1;
    }
};

int main() {
    int N, K;
    cin >> N >> K;

    vector<ll> a(N);
    rep(i, N) cin >> a[i];

    ll ans = a[K - 1];

    vector<int> v;
    rep2(i, K - 1, N) v.eb(i);
    sort(all(v), [&](int i, int j) { return a[i] < a[j]; });
    // print(v);

    auto f = [](ll x, ll y) { return min(x, y); };
    Segment_Tree<ll> seg(a, f, inf);

    Binary_Indexed_Tree<int> bit(N, 0);
    ll S = a[v[0]];
    bit.add(v[0], 1);

    for (int i = 2; K * i <= N; i++) {
        S += a[v[i - 1]];
        bit.add(v[i - 1], 1);
        if (bit.query(0, (K - 1) * (i - 1) + 1) > 0) continue;
        if (bit.query(0, (K - 1) * i + 1) == 0) {
            ll x = seg.query((K - 1) * (i - 1) + 1, (K - 1) * i + 1);
            chmin(ans, S - a[v[i - 1]] + x);
        } else if (bit.query(K * i - 1, N) == 0) {
            ll x = seg.query(K * i - 1, N);
            chmin(ans, S - a[v[i - 1]] + x);
        } else {
            chmin(ans, S);
        }
    }

    cout << ans << '\n';
}