#include "boxes.h"
#include <iostream>
#include <algorithm>
using namespace std;
#define ll long long
const ll N = 1e7;
ll dp1[N * 2];
ll dp2[N * 2];
ll delivery(int n, int k, int l, int p[]) {
sort(p, p + n);
ll ans = N * N;
int i;
ll L = l;
for (i = 0; i < n; i++)
{
if (i < k)
dp1[i] = min(1ll * p[i] * 2, L);
else
dp1[i] = min(1ll * p[i] * 2, L) + dp1[i - k];
}
for (i = n - 1; 0 <= i; i--)
{
if (n - i <= k)
dp2[i] = min(L, 1ll * (L - p[i]) * 2);
else
dp2[i] = min(L, 1ll * (L - p[i]) * 2) + dp2[i + k];
}
ans = dp2[0];
for (i = 0; i < n; i++)
ans = min(dp1[i] + dp2[i + 1], ans);
return ans;
}/*
int n, k, l;
int pp[N];
int main()
{
cin >> n >> k >> l;
for (int i = 0; i < n; i++)
cin >> pp[i];
cout << delivery(n, k, l, pp);
return 0;
}
*/
