#include <algorithm>
#include <iostream>
using namespace std;
typedef long long ll;

const ll INF = 100000000000000000;

int main()
{
    int n, k;
    cin >> n >> k;
    ll a[200005];
    for(int i = 0; i < n; i++) cin >> a[i];
    for(int i = n - 1; i >= 0; i--) a[i] -= a[0];
    ll ans = INF;
    int x = 0;
    if(k * 2 >= n) x = (k * 2 - n) / 2;
    if(k * 2 < n){
        for(int c = 0; c < 2; c++){
            ll s = 0;
            reverse(a, a + n);
            for(int i = 0; i < k; i++) s += abs(a[i] - a[x]);
            for(int i = k; i < n; i++) s -= abs(a[i] - a[x]);
            ans = min(ans, s);
        }
    }
    else{
        ll s = 0;
        ll l = 0;
        for(int i = 0; i < n; i++){
            if(i >= x && i < k){
                s += a[i];
                l--;
            }
            else{
                s -= a[i];
                l++;
            }
        }
        ans = s + a[x] * l;
        for(int i = 0; x + i <= n - 1 - x - 2; i += 2){
            s += (a[i / 2] - a[x + i] - a[x + i + 1] + a[k + i / 2]) * 2;
            ans = min(ans, s + a[x + i + 2] * l);
        }
    }
    cout << ans << endl;
}