#include "boxes.h"
#include <bits/stdc++.h>
#define ff first
#define ss second
#define all(x) (x).begin(), (x).end()
#define pb push_back
using namespace std;
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ld, ld> pld;
const ll inf = 1e18;
int n, k, l;
void calcOneSide(int dist[], ll dp[]){
for(int i = 1; i <= n; ++i){
dp[i] = dp[max(0, i-k)] + 2*dist[i-1];
}
}
ll leftDp[10000009];
ll rightDp[10000009];
long long delivery(int N, int K, int L, int p[]) {
n = N;
k = K;
l = L;
sort(p, p+n);
calcOneSide(p, leftDp);
reverse(p, p+n);
for(int i = 0; i < n; ++i){
p[i] = l-p[i];
}
calcOneSide(p, rightDp);
ll ans = inf;
for(int i = 0; i <= n; ++i){
ll simpAns = leftDp[i] + rightDp[n-i];
ll compAns = leftDp[i] + l + rightDp[max(0, n-i-k)];
ans = min({ans, simpAns, compAns});
}
return ans;
}
