#include <bits/stdc++.h>
#include "boxes.h"
using namespace std;
using ll = long long;
using pii = pair<int, int>;
const int mxN = 1e6+5;
vector<int> pos;
ll delivery(int n, int k, int l, int* a) {
pos.assign(n, 0);
for (int i=0; i<n; i++) {
pos[i] = a[i];
}
vector<ll> L(n, 0), R(n, 0);
for (int i=0; i<k; i++) {
L[i] = 2*(pos[i]);
}
for (int i=n-1; i>=n-k; i--) {
R[i] = 2*(l-pos[i]);
}
for (int i=k; i<n; i++) {
L[i] = L[i-k] + 2*(pos[i]);
}
for (int i=n-k-1; i>=0; i--) {
R[i] = R[i+k] + 2*(l-pos[i]);
}
ll ans=R[0];
for (int i=0; i<n-1; i++) {
ans = min(ans, L[i]+R[i+1]);
}
ans = min(ans, L[n-1]);
for (int i=0; i<n; i++) {
ll left = (i==0 ? 0 : L[i-1]);
ll right = (i+k>=n ? 0 : R[i+k]);
//cout << i << " " << left << " " << right << endl;
ans = min(ans, left+right+l);
}
return ans;
}
//i+k-1-i
//k-1
