#include "boxes.h"
#include <bits/stdc++.h>
using namespace std;
const int M = 10000005;
const long long INF = 1e18;
int arr[2][M];
long long f[M], g[M];
long long delivery(int N, int K, int L, int p[]) {
int pos = -1;
for (int i = 0; i < N; ++i) if (p[i] * 2 <= L) pos = i;
int sz[2];
sz[0] = 0;
for (int i = 0; i <= pos; ++i) arr[0][++sz[0]] = p[i] * 2;
sz[1] = 0;
for (int i = N - 1; i > pos; --i) arr[1][++sz[1]] = (L - p[i]) * 2;
long long res = INF;
for (int i = 0; i <= K; ++i) g[i] = INF;
for (int i = 0; i < 2; ++i) {
for (int j = 1; j <= sz[i]; ++j) {
if (j < K) f[j] = arr[i][j];
else f[j] = f[j - K] + arr[i][j];
}
if (i == 0) {
for (int j = sz[0]; j >= 0; --j) {
if (sz[0] - j > K) break;
g[sz[0] - j] = f[j];
}
}
else {
res = min(res, g[0] + f[sz[1]]);
for (int j = sz[1]; j >= 0; --j) {
if (sz[1] - j > K) break;
res = min(res, g[K - (sz[1] - j)] + f[j] + L);
}
}
}
return res;
}
