#include "boxes.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll MAXN = 2e7 + 10;
ll ps[MAXN], ss[MAXN];
long long delivery(int N, int K, int L, int p[]) {
sort(p, p + N);
ll x = p[N - 1];
x = min(x, ll(L - p[0]));
for (int i = 0; i < N - 1; i++)
x = min(x, ll(p[i]) + L - p[i + 1]);
return 2 * x;
for (int i = 0; i < N; i++) {
ps[i] = numeric_limits<ll>::max();
if (i < K) ps[i] = 2 * p[i];
else {
for (int j = i - 1; j >= i - K; j--)
ps[i] = min(ps[i], ps[j] + 2 * p[i]);
}
}
ss[N] = 0;
for (int i = N - 1; i >= 0; i--) {
ss[i] = numeric_limits<ll>::max();
for (int j = i + 1; j <= i + K; j++)
ss[i] = min(ss[i], ss[j] + 2 * (L - p[i]));
}
ll ans = ps[N - 1];
for (int i = 0; i < N; i++)
ans = min(ans, ps[i] + ss[i + 1]);
return ans;
}
