#include "boxes.h"
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<long long, long long>
#define fr first
#define se second
int n, k, l;
int dist(int a, int b) {
if (a > b) swap(a, b);
if (a == 0) return min(b, l - b);
return min(b - a, dist(0, a) + dist(0, b));
}
int delivery(int32_t N, int32_t K, int32_t L, int32_t p[]) {
n = N, k = K, l = L;
vector<int> v;
v = {0};
for (int i = 0; i < n; i++) v.push_back(p[i]);
v.push_back(l);
// ok
vector<int> pf(n + 1); // how many extras
for (int i = 1; i <= n; i++) {
pf[i] = pf[i - 1];
if (((i - 1) % k) == 0) pf[i] += 2*v[i - 1];
}
for (int i = 1; i <= n; i++) pf[i] += v[i];
// sf
vector<int> sf(n + 2);
for (int i = n; i >= 1; i--) {
sf[i] = sf[i + 1];
if (((n - i) % k) == 0) sf[i] += 2*(l - v[i + 1]);
}
for (int i = 1; i <= n; i++) sf[i] += (l - v[i]);
// ok
int ans = 0x3f3f3f3f3f3f3f3f;
for (int i = 0; i <= n; i++) {
ans = min(ans, pf[i] + sf[i + 1] + dist(0, v[i]) + dist(0, v[i + 1]));
}
//cout << ans << "\n";
return ans;
}
