#include <bits/stdc++.h>
using namespace std;
long long delivery(int N, int K, int L, int p[]) {
vector<long long> l, r;
l = r = {0};
for (int i = 0; i < N; i++) {
l.push_back(p[i]);
r.push_back(L - p[i]);
}
sort(l.begin(), l.end());
sort(r.begin(), r.end());
for (int i = 1; i <= N; i++) {
l[i] *= 2; if (i >= K) l[i] += l[i - K];
r[i] *= 2; if (i >= K) r[i] += r[i - K];
}
// for (int x : l) cout << x << ' '; cout << endl;
// for (int x : r) cout << x << ' '; cout << endl;
long long ans = (long long) 1e18;
for (int i = 0; i <= N; i++) {
ans = min(ans, l[i] + r[N - i]);
ans = min(ans, l[i] + r[max(0, N - i - K)] + (long long) L);
}
// cout << ans << endl;
return ans;
}
