#include "boxes.h"
#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e18;
long long delivery(int N, int K, int L, int p[]) {
vector<int> positions(N);
for(int i = 0; i < N; i ++) positions[i] = p[i];
sort(positions.begin(), positions.end());
/*for(int i = 0; i < N; i ++) {
if(positions[i] == 0) {
K -- ;
positions.erase(positions.begin());
}
}*/
vector<long long> f(N);
vector<long long> s(N);
for(int i = 0, j = 0; i < N; i ++) {
j = max(j, i - K + 1);
f[i] = (j == 0 ? 0 : f[j - 1]) + positions[i] * 2;
}
for(int i = N - 1, j = N - 1; i >= 0; i --) {
j = min(j, i + K - 1);
s[i] = (j == N - 1 ? 0 : s[j + 1]) + (L - positions[i]) * 2;
}
long long ans = INF;
for(int i = 0; i < N; i ++) {
ans = min(ans, (i > 0 ? f[i - 1] : 0) + (i < N ? s[i] : 0));
ans = min(ans, (i >= 0 ? f[i] : 0) + (i + 1 < N ? s[i + 1] : 0));
//cout << i << " " << (i > 0 ? f[i - 1] : 0) + (i < N ? s[i] : 0) << "\n";
//cout << i << " " << (i >= 0 ? f[i] : 0) + (i + 1 < N ? s[i + 1] : 0) << "\n";
}
for(int i = 0, j = 0; i < N; i ++) {
j = max(j, i - K + 1);
ans = min(ans, (j > 0 ? f[j - 1] : 0) + (i + 1 < N ? s[i + 1] : 0) + L);
}
return ans;
}
/*int main() {
int N, K, L;
cin >> N >> K >> L;
int p[N];
for(int i = 0; i < N; i ++) cin >> p[i];
cout << delivery(N, K, L, p) << "\n";
return 0;
}*/
