#include "boxes.h"
#include <bits/stdc++.h>
#define ll long long
using namespace std;
ll delivery(int n, int k, int L, int p[]) {
vector<int> left {};
vector<int> right {};
for (int i = 0; i < n; i++) {
if (p[i] > L / 2)
right.push_back(p[i]);
else
left.push_back(p[i]);
}
if (!right.empty())
reverse(right.begin(), right.end());
vector<ll> mLeft {};
vector<ll> mRight {};
mLeft.push_back(0);
mRight.push_back(0);
for (int i = 0; i < (int)left.size(); i++) {
mLeft.push_back(2 * left[i]);
if (i + 1 > k)
mLeft.back() += mLeft[i + 1 - k];
//cout << "mleft " << mLeft.back() << '\n';
}
for (int i = 0; i < (int)right.size(); i++) {
mRight.push_back(2 * (L - right[i]));
if (i + 1 > k)
mRight.back() += mRight[i + 1 - k];
}
ll ans = mLeft.back() + mRight.back();
for (int lstLeft = max(0, (int)left.size() - k); lstLeft <= (int)left.size(); lstLeft++) {
//cout << "lst " << lstLeft << '\n';
int cutFromLeft = (int)left.size() - lstLeft;
int lstRight = max(0, (int)right.size() - (k - cutFromLeft));
ll cur = mLeft[lstLeft] + mRight[lstRight] + L;
ans = min(ans, cur);
}
return ans;
}
