#include "boxes.h"
#include <algorithm>
#include <iostream>
#include <numeric>
#include <cassert>
#include <vector>
typedef long long llong;
const int MAXN = 10000000 + 10;
const llong INF = 1e18;
int n, k, l;
std::vector <int> left;
std::vector <int> right;
llong prefix[MAXN];
llong suffix[MAXN];
llong calcLeft(int to)
{
llong res = 0;
for (int i = to ; i >= 0 ; i -= k)
{
res += 2 * left[i];
}
return res;
}
llong calcRight(int to)
{
llong res = 0;
for (int i = to ; i < n ; i += k)
{
res += 2 * right[i];
}
return res;
}
llong delivery(int N, int K, int L, int p[])
{
n = N;
k = K;
l = L;
if (k > n) k = n;
for (int i = 0 ; i < n ; ++i)
{
left.push_back(p[i]);
right.push_back(l - p[i]);
}
for (int i = 0 ; i < n ; ++i)
{
prefix[i] = 2 * left[i];
if (i > 0)
{
prefix[i] += prefix[i - 1];
if (i % k != 0)
{
prefix[i] -= 2 * left[i - 1];
}
}
}
for (int i = n - 1 ; i >= 0 ; --i)
{
suffix[i] = 2 * right[i];
suffix[i] += suffix[i + 1];
if ((n - 1 - i) % k != 0)
{
suffix[i] -= 2 * right[i + 1];
}
}
llong ans = calcRight(0);
for (int i = 0 ; i < n ; ++i)
{
ans = std::min(ans, calcLeft(i) + calcRight(i + 1));
}
for (int i = 0 ; i + k <= n ; ++i)
{
llong curr = l + calcRight(i + k);
if (i > 0) curr += calcLeft(i - 1);
ans = std::min(ans, curr);
}
return ans;
}
