//#pragma GCC optimize ("O2")
//#pragma GCC target ("avx2")
#include<bits/stdc++.h>
//#include<atcoder/all>
//using namespace atcoder;

using namespace std;
typedef long long ll;
#define rep(i, n) for(int i = 0; i < (n); i++)
#define rep1(i, n) for(int i = 1; i <= (n); i++)
#define co(x) cout << (x) << "\n"
#define cosp(x) cout << (x) << " "
#define ce(x) cerr << (x) << "\n"
#define cesp(x) cerr << (x) << " "
#define pb push_back
#define mp make_pair
#define chmin(x, y) x = min(x, y)
#define chmax(x, y) x = max(x, y)
#define Would
#define you
#define please


int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);


	int N, K;
	cin >> N >> K;
	ll A[200001];
	rep(i, N) cin >> A[i];
	A[N] = 2e18;

	int L = 0, R = K;
	ll kari = 0;
	rep(i, R) kari += A[i];
	for (int i = R; i < N; i++) kari -= A[i];
	ll kotae = 1e18;
	chmin(kotae, kari - A[0] * (R + R + L + L - N));
	ce(kotae);

	rep1(i, N - 1) {
		kari -= 2 * A[i - 1];

		ll X = A[i];
		while (X - A[L] > A[R] - X) {
			kari += 2 * A[L];
			kari += 2 * A[R];
			L++;
			R++;
		}
		//cesp(L);
		//cesp(R);
		//cesp(kari);
		//ce(kari - X * (R + R - i - i + L + L - N));

		chmin(kotae, kari - X * (R + R - i - i + L + L - N));

	}
	co(kotae);

	Would you please return 0;
}