#include "boxes.h"
#include<algorithm>
#include<iomanip>
#include<vector>
#include<set>
#include<iterator>
#include<iostream>
using namespace std;
#define ll long long
#define vi vector<ll>
#define vvi vector<vi>
#define ms multiset<int>
ms M;
int glt, grt;
int k, n, l;
ll ans;
ll oink(int le = 1) {
ans = 0;
int lt = glt, rt = grt;
auto it = M.begin();
int re = n%k-le;
if (le != 0) {
advance(it, le-1);
ans += 2*(*it);
lt -= le;
it++;
}
while (lt >= k) {
advance(it, k-1);
ans += 2*(*it);
lt -= k;
it++;
}
it = M.end();
if (re != 0) {
advance(it, -re);
ans += 2*(*it);
rt -= re;
}
while (rt >= k) {
advance(it, -k);
ans += 2*(l-(*it));
rt -= k;
}
if (lt == 0 && rt == 0) return ans;
//cerr << "oink ans : " << ans + l << endl;
return ans + l;
}
ll oinkoink() {
ans = 0;
auto it = M.begin();
advance(it, glt);
auto it1 = it;
it++;
auto it2 = it;
while (distance(M.begin(), it1) >= k) {
ans += 2*(*it1);
advance(it1, -k);
}
ans += 2*(*it1);
while (distance(it2, M.end()) > k) {
ans += 2*(*it2);
advance(it2, -k);
}
ans += 2*(l-(*it2));
return ans;
}
ll delivery(int in, int ik, int il, int p[]) {
k = ik;
n = in;
l = il;
ans = 0;
M.clear();
int lh = l/2;
for (int i = 0; i < n; i++) {
M.insert(p[i]);
if (p[i] <= lh) glt++;
else grt++;
}
ll best = oinkoink();
//cerr << "best no circle : " << best << endl;
for (int i = 1; i < k; i++) {
best = min(best, oink(i));
//cerr << "best: " << best << endl;
}
return best;
}
