#include <bits/stdc++.h>
#include "boxes.h"
using namespace std;
#define ll long long
ll dpFOR[10000002];
ll dpBACK[10000002];
ll a[10000002];
ll res = 1010101010;
long long delivery(int N, int K, int L, int p[]) {
for (int i = 1; i <= N; i++)
a[i] = p[i - 1];
for (int i = 1; i <= N; i++) {
if (i <= K)dpFOR[i] = a[i] + min(a[i], L - a[i]);
else dpFOR[i] = dpFOR[i - K] + a[i] + min(a[i], L - a[i]);
}
for (int i = N; i >= 1; i--) {
if (N - i + 1 <= K)dpBACK[i] = (L - a[i]) + min(a[i], L - a[i]);
else dpBACK[i] = dpBACK[i + K] + (L - a[i]) + min(a[i], L - a[i]);
}
// for (int i = 1; i <= N; i++) {
// cout << dpFOR[i] << " ";
// }
// cout << endl;
// for (int i = 1; i <= N; i++) {
// cout << dpBACK[i] << " ";
// }
// cout << endl;
res = min(dpFOR[N], dpBACK[1]);
for (int i = 1; i < N; i++) {
res = min(res, dpFOR[i] + dpBACK[i + 1]);
}
return res;
}
/**
3 2 8
1 2 5
*/
