#include <bits/stdc++.h>

using namespace std;

using ll = long long;

constexpr char newl = '\n';

template<class U = ll, class V = U>
struct Nothing {
    using Tm = U;
    using To = V;
    static Tm merge(const Tm& x, const Tm& y) { return unit(); }
    static To op_merge(const To& x, const To& y) { return op_unit(); }
    static Tm apply(const Tm& vm, const To& vo, size_t seg_len) { return vm; }
    static constexpr Tm unit() { return Tm(0); }
    static constexpr To op_unit() { return To(0); }
};

// https://www.slideshare.net/iwiwi/2-12188757
// https://tubo28.me/compprog/algorithm/treap/
// https://ei1333.github.io/luzhiled/snippets/structure/rbst.html
// https://qiita.com/tubo28/items/f058582e457f6870a800
template <class MonoidOp = Nothing<> >
class Treap {
public:
    using Tm = typename MonoidOp::Tm;
    using To = typename MonoidOp::To;

private:
    inline static unsigned int randxor() noexcept {
        static unsigned int x=123456789,y=362436069,z=521288629,w=88675123;
        unsigned int t;
        t=(x^(x<<11));x=y;y=z;z=w; return( w=(w^(w>>19))^(t^(t>>8)) );
    }

public:
    struct Node {
        unsigned int pri;
        size_t sz;
        Tm val, sum;
        To lazy;
        unique_ptr<Node> lch, rch;

        Node(const Tm& x) : pri(randxor()), sz(1), val(x), sum(x), lazy(MonoidOp::op_unit()) {}

        static constexpr size_t size(const unique_ptr<Node>& node) noexcept {
            return (!node ? 0 : node->sz);
        }

        static constexpr Tm getSum(const unique_ptr<Node>& node) noexcept {
            return (!node ? MonoidOp::unit() : node->sum);
        }
    };

private:
    inline static unique_ptr<Node>& update(unique_ptr<Node>& node) noexcept {
        node->sz = Node::size(node->lch) + Node::size(node->rch) + 1;
        node->sum = MonoidOp::merge(MonoidOp::merge(Node::getSum(node->lch), node->val), Node::getSum(node->rch));
        return node;
    }

    inline static unique_ptr<Node>& push(unique_ptr<Node>& node) noexcept {
        if (node->lazy == MonoidOp::op_unit()) return update(node);

        node->val = MonoidOp::apply(node->val, node->lazy, 1);

        if (node->lch) {
            node->lch->lazy = MonoidOp::op_merge(node->lch->lazy, node->lazy);
            node->lch->sum = MonoidOp::apply(node->lch->sum, node->lazy, Node::size(node->lch));
        }

        if (node->rch) {
            node->rch->lazy = MonoidOp::op_merge(node->rch->lazy, node->lazy);
            node->rch->sum = MonoidOp::apply(node->rch->sum, node->lazy, Node::size(node->rch));
        }

        node->lazy = MonoidOp::op_unit();
        return update(node);
    }

    // split into [0, pos), [pos, size(node))
    static pair< unique_ptr<Node>, unique_ptr<Node> > split(unique_ptr<Node> node, size_t pos) noexcept {
        if (!node) return pair< unique_ptr<Node>, unique_ptr<Node> >();

        assert(pos <= Node::size(node));

        push(node);
        if (pos <= Node::size(node->lch)) {
            auto p = split(move(node->lch), pos);
            node->lch = move(p.second);
            return {move(p.first), move(update(node))};
        } else {
            auto p = split(move(node->rch), pos - Node::size(node->lch) - 1);
            node->rch = move(p.first);
            return {move(update(node)), move(p.second)};
        }
    }

    static unique_ptr<Node> merge(unique_ptr<Node> nodeL, unique_ptr<Node> nodeR) noexcept {
        if (!nodeR) return nodeL;
        if (!nodeL) return nodeR;

        if (nodeL->pri > nodeR->pri) {
            push(nodeL);
            nodeL->rch = merge(move(nodeL->rch), move(nodeR));
            return move(update(nodeL));
        } else {
            push(nodeR);
            nodeR->lch = merge(move(nodeL), move(nodeR->lch));
            return move(update(nodeR));
        }
    }

    static void insert(unique_ptr<Node>& node, size_t pos, const Tm& val) noexcept {
        auto p = split(move(node), pos);
        auto tmp = merge(move(p.first), move(unique_ptr<Node>(new Node(val))));
        node = move(merge(move(tmp), move(p.second)));
    }

    static void erase(unique_ptr<Node>& node, size_t pos) noexcept {
        if (!node) return;

        assert(pos < Node::size(node));

        auto pr = split(move(node), pos + 1);
        auto pl = split(move(pr.first), pos);

        node = merge(move(pl.first), move(pr.second));
    }

    static void update(unique_ptr<Node>& node, size_t a, size_t b, const To& x) noexcept {
        auto p1 = split(move(node), b);
        auto p2 = split(move(p1.first), a);
        p2.second->lazy = MonoidOp::op_merge(p2.second->lazy, x);
        node = merge(merge(move(p2.first), move(push(p2.second))), move(p1.second));
    }

    static Tm query(unique_ptr<Node>& node, size_t a, size_t b) noexcept {
        auto p1 = split(move(node), b);
        auto p2 = split(move(p1.first), a);
        Tm res = Node::getSum(p2.second);
        node = merge(merge(move(p2.first), move(p2.second)), move(p1.second));
        return res;
    }

    static void set(unique_ptr<Node>& node, size_t pos, const Tm& x) {
        push(node);
        if (pos < Node::size(node->lch)) set(node->lch, pos, x);
        else if (pos == Node::size(node->lch)) node->val = x;
        else set(node->rch, pos - Node::size(node->lch) - 1, x);
        update(node);
    }

    static unique_ptr<Node> build(size_t l, size_t r, const vector<Tm>& v) {
        if (l + 1 >= r) return unique_ptr<Node>(new Node(v[l]));
        return merge(build(l, (l + r) >> 1, v), build((l + r) >> 1, r, v));
    }

    static void dump(unique_ptr<Node>& node) noexcept {
        if (!node) return;

        push(node);
        dump(node->lch);
        cerr << node->val << " ";
        dump(node->rch);
    }

public:
    unique_ptr<Node> root;

public:
    Treap(unique_ptr<Node>& node) : root(move(node)) {}

public:
    Treap() = default;
    Treap(size_t sz, const Tm& initial_value = MonoidOp::unit()) {
        vector<Tm> v(sz, initial_value);
        root = build(0, sz, v);
    }

    Treap(const vector<Tm>& v) {
        root = build(0, v.size(), v);
    }

    constexpr bool empty() const noexcept {
        return !root;
    }

    constexpr size_t size() const noexcept {
        return Node::size(root);
    }

    // // split into [0, pos), [pos, size())
    // [WARNING!!!]: Don't use this Treap after split
    inline pair< Treap, Treap > split(size_t pos) noexcept {
        auto p = split(move(root), pos);
        return {Treap(p.first), Treap(p.second)};
    }

    // merge tree from the right of this Treap
    // [WARNING!!!]: Don't use tree after merge
    inline void merge(Treap& tree) noexcept {
        root = merge(move(root), move(tree.root));
    }

    inline void insert_at(size_t pos, const Tm& val) noexcept {
        insert(root, pos, val);
    }

    inline void erase_at(size_t pos) noexcept {
        erase(root, pos);
    }

    // [a, b)
    inline void update(size_t a, size_t b, const To& x) {
        update(root, a, b, x);
    }

    // [a, b)
    inline Tm query(size_t a, size_t b) noexcept {
        return query(root, a, b);
    }

    inline Tm get(size_t pos) noexcept {
        return query(pos, pos + 1);
    }

    inline void set(size_t pos, const Tm& x) {
        set(root, pos, x);
    }

    inline void dump() noexcept {
        cerr << "Seq: ";
        dump(root);
        cerr << newl;
    }
};

// 以下、MonoidOpの例
template<class U = ll, class V = U>
struct RangeSumAdd {
    using Tm = U;
    using To = V;
    static Tm merge(Tm x, Tm y) { return x + y; }
    static To op_merge(To x, To y) { return x + y; }
    static Tm apply(Tm vm, To vo, int seg_len) { return vm + vo * seg_len; }
    static constexpr Tm unit() { return Tm(0); }
    static constexpr To op_unit() { return To(0); }
};

template<class U = ll, class V = U>
struct RangeMinUpdate {
    using Tm = U;
    using To = V;
    static Tm merge(Tm x, Tm y) { return min(x, y); }
    static To op_merge(To x, To y) { return y; }
    static Tm apply(Tm vm, To vo, int seg_len) { return vo == op_unit() ? vm : vo; }
    static constexpr Tm unit() { return numeric_limits<Tm>::max(); }
    static constexpr To op_unit() { return numeric_limits<To>::max(); }
};

// 作用素の初期値は更新クエリで与えられる値の定義域の範囲外の値にする
template<class U = ll, class V = U>
struct RangeSumUpdate {
    using Tm = U;
    using To = V;
    static Tm merge(Tm x, Tm y) { return x + y; }
    static To op_merge(To x, To y) { return y; }
    static Tm apply(Tm vm, To vo, int seg_len) { return vo == op_unit() ? vm : vo * seg_len; }
    static constexpr Tm unit() { return Tm(0); }
    static constexpr To op_unit() { return numeric_limits<To>::min(); }
};

// 初期値 != 単位元 の場合に注意
template<class U = ll, class V = U>
struct RangeMinAdd {
    using Tm = U;
    using To = V;
    static Tm merge(Tm x, Tm y) { return min(x, y); }
    static To op_merge(To x, To y) { return x + y; }
    static Tm apply(Tm vm, To vo, int seg_len) { return vm + vo; }
    static constexpr Tm unit() { return numeric_limits<Tm>::max(); }
    static constexpr To op_unit() { return To(0); }
};

// [Depends on]: Treap
template<class T>
class OrderedMultiSet : public Treap< RangeSumAdd<T> > {
public:
    using Tree = Treap< RangeSumAdd<T> >;
    using Node = typename Tree::Node;

private:
    static T at(const unique_ptr<Node>& node, size_t pos) noexcept {
        if (pos < Node::size(node->lch)) return at(node->lch, pos);
        if (pos == Node::size(node->lch)) return node->val;
        return at(node->rch, pos - Node::size(node->lch) - 1);
    }

    static size_t lower_bound(const unique_ptr<Node>& node, T val) noexcept {
        if (!node) return 0;
        if (val <= node->val) return lower_bound(node->lch, val);
        return lower_bound(node->rch, val) + Node::size(node->lch) + 1;
    }

    static size_t upper_bound(const unique_ptr<Node>& node, T val) noexcept {
        if (!node) return 0;
        if (val < node->val) return upper_bound(node->lch, val);
        return upper_bound(node->rch, val) + Node::size(node->lch) + 1;
    }

    static bool contains(const unique_ptr<Node>& node, T val) noexcept {
        if (!node) return false;
        if (val == node->val) return true;
        if (val < node->val) return contains(node->lch, val);
        else return contains(node->rch, val);
    }

    // Use these function only inside
    void insert_at(size_t, const typename Tree::Tm&);
    void erase_at(size_t);

public:
    using Tree::Treap;

    // Note: https://qiita.com/matsumoto_sp/items/233503b4a31dc1f190b6
    OrderedMultiSet() = default;
    OrderedMultiSet(Tree& t) : OrderedMultiSet(t.root) {}
    OrderedMultiSet(const vector<T>& v) : Tree::Treap(v) {
        assert(is_sorted(v.begin(), v.end()));
    }

    // Don't use these functions
    //void update(size_t, size_t, const typename Tree::To&) = delete;
    //typename Tree::Tm query(size_t, size_t, const typename Tree::To&) = delete;
    //typename Tree::Tm get(size_t) = delete;
    //void set(size_t, const typename Tree::Tm&) = delete;

    inline T at(size_t pos) noexcept {
        assert(pos < Tree::size());
        return at(Tree::root, pos);
    }

    // return position (index)
    // if val doesn't exist, return size()
    inline size_t find(T val) noexcept {
        return (contains(val) ? lower_bound(val) : Tree::size());
    }

    // return position (index)
    inline size_t lower_bound(T val) noexcept {
        return lower_bound(Tree::root, val);
    }

    // return position (index)
    inline size_t upper_bound(T val) noexcept {
        return upper_bound(Tree::root, val);
    }

    inline bool contains(T val) noexcept {
        return contains(Tree::root, val);
    }

    inline size_t count(T val) noexcept {
        return upper_bound(val) - lower_bound(val);
    }

    inline virtual void insert(T val) noexcept {
        Tree::insert_at(lower_bound(val), val);
    }

    inline void erase(T val) noexcept {
        if (!contains(val)) return;
        Tree::erase_at(lower_bound(val));
    }
};

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    int q, K;
    cin >> q >> K;

    vector<ll> a(q);
    for (int i = 0; i < q; i++) {
        cin >> a[i];
    }

    OrderedMultiSet<ll> s;
    ll ans = 1e18;
    for (int i = 0; i < q; i++) {
        if (i >= K) {
            s.erase(a[i - K]);
        }

        s.insert(a[i]);

        if (s.size() == K) {
            ll tar = s.at(K / 2);
            auto p = s.split(K / 2);

            ll sz1 = p.first.size(), sz2 = p.second.size();
            ans = min(ans, tar * sz1 - p.first.query(0, sz1) + p.second.query(0, sz2) - tar * sz2);
            p.first.merge(p.second);
            s = OrderedMultiSet<ll>(p.first);
        }
    }
    cout << ans << newl;

    return 0;
}