#include "boxes.h"
#include <bits/stdc++.h>
#define X first
#define Y second
#define pb push_back
#define pii pair<int, int>
typedef long long ll;
using namespace std;
const int MOD = 1e9 + 7;
const ll INF = 1e18;
const int OFF = (1 << 20);
ll l[10000005];
ll r[10000005];
vector<int> v;
long long delivery(int n, int k, int d, int p[]) {
for (int i = 0; i < n; i++) {
if (p[i] != 0) v.push_back(p[i]);
}
for (int i = 0; i < (int)v.size(); i++) {
if (i < k) l[i] = 2*v[i];
else l[i] = 2*v[i]+l[i-k];
}
for (int i = (int)v.size()-1; i >= 0; i--) {
if ((int)v.size() - i <= k) r[i] = 2*(d-v[i]);
else r[i] = 2*(d-v[i])+r[i+k];
}
ll sol = min(r[0], l[(int)v.size()-1]);
for (int i = 0; i < (int)v.size()-1; i++) {
sol = min(sol, l[i]+r[i+1]);
}
for (int i = 0; i+k+1 < (int)v.size(); i++) {
sol = min(sol, l[i]+r[i+k+1]+d);
}
return sol;
}
