#include <bits/stdc++.h>
#define forint(i, N) for (int i = 0; i < (N); i++)
using namespace std;
typedef long long ll;
ll delivery(int n, int k, int l, int p[]) {
vector<int> dist(n);
for (int i = 0; i < n; i++) {
dist[i] = min(p[i], l - p[i]);
}
vector<ll> costl(n);
vector<ll> costr(n);
costl[0] = 2 * dist[0];
for (int i = 1; i < n; i++) {
costl[i] = i >= k ? (ll)(costl[i - k] + p[i] + dist[i]) : (ll)(p[i] + dist[i]);
}
costr[n - 1] = 2 * dist[n - 1];
for (int i = n - 2; i >= 0; i--) {
costr[i] = i + k < n ? (ll)(costr[i + k] + l - p[i] + dist[i]) : (ll)(l - p[i] + dist[i]);
}
ll ret = min(costl[n - 1], costr[0]);
forint(i, n - 1) {
if (costl[i] + costr[i + 1] < ret) ret = costl[i] + costr[i + 1];
}
/*forint(i, n) {
cerr << costl[i] << " - " << costr[i] << endl;
}*/
return ret;
}
