#include "boxes.h"
#include <bits/stdc++.h>
using namespace std;
template<typename T>
using min_heap = priority_queue<T, vector<T>, greater<T>>;
template<typename T>
using max_heap = priority_queue<T, vector<T>, less<T>>;
using int64 = long long;
using ld = long double;
constexpr int kInf = 1e9 + 10;
constexpr int64 kInf64 = 1e15 + 10;
constexpr int kMod = 1e9 + 7;
long long delivery(int N, int K, int L, int p[]) {
vector<int> pos(N + 1);
for (int i = 1; i <= N; i++) {
pos[i] = p[i - 1];
}
sort(pos.begin(), pos.end());
vector<int64> l(N + 1);
vector<int64> r(N + 2);
for (int i = 1; i <= N; i++) {
l[i] = l[max(0, i - K)] + 2 * pos[i];
}
for (int i = N; i > 0; i--) {
r[i] = r[min(N + 1, i + K)] + 2 * (L - pos[i]);
}
int64 ans = min(r[1], l[N]);
for (int i = 1; i < N; i++) {
ans = min(ans, l[i] + r[i + 1]);
}
for (int i = 1; i <= N; i++) {
const int64 lt = l[i - 1];
const int64 rt = (i + K <= N ? r[i + K] : 0);
ans = min(ans, lt + rt + L);
}
return ans;
}
