#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 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 >= k) prefix[i] += prefix[i - k];
}
for (int i = n - 1 ; i >= 0 ; --i)
{
suffix[i] = 2 * right[i];
if (i + k < n) suffix[i] += suffix[i + k];
}
llong ans = suffix[0];
for (int i = 0 ; i < n ; ++i)
{
ans = std::min(ans, prefix[i] + suffix[i + 1]);
}
for (int i = 0 ; i + k <= n ; ++i)
{
llong curr = l + suffix[i + k];
if (i > 0) curr += prefix[i - 1];
ans = std::min(ans, curr);
}
return ans;
}
