#include <bits/stdc++.h>
#include "boxes.h"
#define pb push_back
#define eb emplace_back
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define uniq(x) x.erase(unique(all(x)), x.end())
#define rall(x) x.rbegin(), x.rend()
//#define int long long
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
const int mod = 1e9 + 7;
const int LOG = 20;
const int maxn = 1e5 + 5;
const double eps = 1e-9;
void setIO() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
}
ll delivery(int N, int K, int L, int pos[]) {
sort(pos, pos + N);
vector<ll> left(N, 0);
vector<ll> right(N, 0);
for(int i=0; i<N; i++) {
if(i < K) left[i] = pos[i] + min(pos[i], L - pos[i]);
else left[i] = left[i-K] + pos[i] + min(pos[i], L - pos[i]);
}
for(int i=N-1; i>=0; i--) {
if(N - 1 < K + i) right[i] = L - pos[i] + min(pos[i], L - pos[i]);
else right[i] = right[i+K] + L - pos[i] + min(pos[i], L - pos[i]);
}
ll ans = min(left[N-1], right[0]);
for(int i=0; i<N-1; i++)
ans = min(ans, left[i] + right[i+1]);
return ans;
}
