#ifndef LOCAL
#include <bits/stdc++.h>

using namespace std;

#define debug(...) (void(0))
#else
#include "algo/debug.h"
#endif

template <class T>
struct FenwickTree {
   private:
    int n;
    int pw;
    std::vector<T> dat;

   public:
    FenwickTree(int m = 0) { init(m); }

    void init(int m) {
        n = m;
        pw = std::bit_floor((unsigned int)n);
        dat.assign(n, T{});
    }

    void add(int p, const T& x) {
        assert(0 <= p && p < n);
        for (p += 1; p <= n; p += p & -p) {
            dat[p - 1] += x;
        }
    }

    T sum(int l, int r) const {
        assert(0 <= l && l <= r && r <= n);
        return sum(r) - sum(l);
    }

    int select(T x) const {
        int at = 0;
        for (int len = pw; len > 0; len >>= 1) {
            if (at + len <= n && dat[at + len - 1] <= x) {
                at += len;
                x -= dat[at - 1];
            }
        }
        assert(0 <= at && at <= n);
        return at;
    }

   private:
    T sum(int r) const {
        T ans{};
        for (; r > 0; r -= r & -r) {
            ans += dat[r - 1];
        }
        return ans;
    }
};

void solve() {
    int N, K;
    cin >> N >> K;
    vector<int> A(N);
    for (int i = 0; i < N; i++) cin >> A[i];
    vector<int> cc;
    for (const auto& x : A) cc.push_back(x);
    sort(cc.begin(), cc.end());
    cc.erase(unique(cc.begin(), cc.end()), cc.end());
    FenwickTree<int> st(N);
    FenwickTree<int64_t> fw(N);
    const auto Add = [&](int p, int x, int64_t a) {
        int y = distance(cc.begin(), lower_bound(cc.begin(), cc.end(), p));
        st.add(y, x);
        fw.add(y, a);
    };
    int64_t ans = 1e18;
    int64_t sum = 0;
    for (int i = 0; i < N; i++) {
        if (i < K - 1) {
            Add(A[i], 1, A[i]);
            sum += A[i];
        } else {
            Add(A[i], 1, A[i]);
            sum += A[i];
            int id = st.select(K / 2);
            int64_t res = int64_t(2 * st.sum(0, id) - K) * cc[id] + sum - 2LL * fw.sum(0, id);
            ans = min(ans, res);
            Add(A[i - K + 1], -1, -A[i - K + 1]);
            sum -= A[i - K + 1];
        }
    }
    cout << ans << endl;
}

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    int tt = 1;
    // std::cin >> tt;
    while (tt--) {
        solve();
    }
}