#include <bits/stdc++.h>
#include "boxes.h"
#define startt ios_base::sync_with_stdio(false);cin.tie(0);
typedef long long ll;
using namespace std;
#define vint vector<int>
#define all(v) v.begin(), v.end()
#define MOD 1000000007
#define MOD2 998244353
#define MX 1000000000
#define MXL 1000000000000000000
#define PI (ld)2*acos(0.0)
#define nax 200005
#define pb push_back
#define sc second
#define fr first
//#define int unsigned long long
//#define endl '\n'
#define ld long double
#define NO cout << "NO" << endl
#define YES cout << "YES" << endl
const int N = 1005;
ll cw[N];
ll ccw[N];
long long delivery(int n, int k, int l, int a[])
{
sort(a, a+n);
for(int i = 0; i < n; i++)
{
if(i%k == 0)
{
int last = 0;
if(i != 0)
{
last = a[i-1];
}
cw[i] = last+a[i];
}
else
{
cw[i] = cw[i-1]+a[i]-a[i-1];
}
}
for(int i = n-1; i >= 0; i--)
{
if((n-1-i)%k == 0)
{
int last = l;
if(i != n-1)
{
last = a[i+1];
}
ccw[i] = l-last+l-a[i];
}
else
{
ccw[i] = ccw[i+1]+a[i+1]-a[i];
}
}
long long ans = MXL;
for(int i = 0; i <= n; i++)
{
if(i == 0)
{
ll option = ccw[0]+l-a[0];
ans = min(ans, option);
continue;
}
if(i == n)
{
ll option = cw[n-1]+a[n-1];
ans = min(ans, option);
continue;
}
ll option = cw[i-1]+ccw[i]+a[i-1]+l-a[i];
ans = min(ans, option);
}
if(k >= n)
{
ans = min(ans, l*1LL);
}
else
{
for(int i = k-1; i < n; i++)
{
if(i-k == -1)
{
ll option = l+ccw[i+1]+l-a[i+1];
ans = min(ans, option);
continue;
}
if(i == n-1)
{
ll option = cw[i-k]+a[i-k]+l;
ans = min(ans, option);
continue;
}
ll option = cw[i-k]+ccw[i+1]+a[i]+l-a[i+1]+l;
ans = min(ans, option);
}
}
return ans;
}
/*
int main()
{
int n, k, l;
cin >> n >> k >> l;
int a[n];
for(int i = 0; i < n; i++)
{
cin >> a[i];
}
cout << delivery(n, k, l, a) << endl;
}
*/
/*
3 2 8
1 2 5
4 3 8
1 3 4 6
*/
