#include "boxes.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 1e7 + 10;
const ll inf = 1e18;
int n, k, L, a, b, A[maxn], B[maxn];
ll dp[maxn], pd[maxn], DP[maxn], opt[maxn], C[maxn];
void calc(int l, int r, int lo, int hi){
if (l >= r)
return;
int m = (l+r) >> 1;
DP[m] = inf;
for (int i = lo; i < hi; i++){
ll x = dp[m] + pd[i];
int cnt = n-m-i;
cnt = (cnt+k-1)/k;
x += 1LL*cnt*L;
if (x < DP[m])
DP[m] = x, opt[m] = i, C[m] = cnt;
}
calc(l, m, lo, hi);
calc(m+1, r, lo, hi);
}
ll delivery(int N, int K, int LL, int p[]){
n = N, k = K, L = LL;
for (int i = 0; i < n; i++){
if (p[i] <= L/2)
A[++a] = p[i];
else
B[++b] = L-p[i];
}
sort(A+1,A+a+1);
sort(B+1,B+b+1);
for (int i = 1; i <= a; i++){
if (i <= k)
dp[i] = 2LL*A[i];
else
dp[i] = dp[i-k] + 2LL*A[i];
}
for (int i = 1; i <= b; i++){
if (i <= k)
pd[i] = 2LL*B[i];
else
pd[i] = pd[i-k] + 2LL*B[i];
}
calc(0, a+1, 0, b+1);
for (int i = 0; i < a; i++)
assert(C[i] >= C[i+1]);
return *min_element(DP, DP+a+1);
}
