#include "boxes.h"
#include <vector>
#include <algorithm>
#include <iostream>
#define debug(x) #x << " = " << x << '\n'
long long delivery(int n, int k, int L, int p[]) {
std::vector<std::pair<int, int>> v(n);
for (int i = 0; i < n; i++) {
v[i].first = std::min(p[i], L - p[i]);
v[i].second = p[i];
}
std::sort(v.begin(), v.end());
std::reverse(v.begin(), v.end());
long long answer = 0;
std::vector<int> st, dr;
for (int i = 0; i < n; i++) {
if (v[i].first == v[i].second) {
st.push_back(v[i].first);
} else {
dr.push_back(v[i].first);
}
}
std::sort(st.begin(), st.end());
std::sort(dr.begin(), dr.end());
while (!st.empty() && !dr.empty() && 2 * std::max(st.back(), dr.back()) >= L) {
answer += L;
for (int i = 0; i < std::min(n, k); i++){
if (v.back().first == v.back().second) {
st.pop_back();
} else {
dr.pop_back();
}
v.pop_back();
}
n = std::max(0, n - k);
}
while (!st.empty()) {
answer += 2 * st.back();
for (int i = 0; i < k && !st.empty(); i++) {
st.pop_back();
}
}
while (!dr.empty()) {
answer += 2 * dr.back();
for (int i = 0; i < k && !dr.empty(); i++) {
dr.pop_back();
}
}
return answer;
}
