#include "boxes.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define int ll
typedef pair<int,int> pi;
typedef vector <int> vi;
typedef vector <pi> vpi;
typedef pair<pi, ll> pii;
typedef set <ll> si;
typedef long double ld;
#define f first
#define s second
#define mp make_pair
#define FOR(i,s,e) for(int i=s;i<=int(e);++i)
#define DEC(i,s,e) for(int i=s;i>=int(e);--i)
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define lbd(x, y) lower_bound(all(x), y)
#define ubd(x, y) upper_bound(all(x), y)
#define aFOR(i,x) for (auto i: x)
#define mem(x,i) memset(x,i,sizeof x)
#define fast ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0)
#define maxn 10000010
#define INF (ll)1e9
#define MOD 1000000007
typedef pair <vi, int> pvi;
typedef pair <int,pi> ipi;
typedef vector <pii> vpii;
int pre[maxn], post[maxn];
long long delivery(int32_t N, int32_t K, int32_t L, int32_t p[]) {
int cur = 0;
FOR(i,0,N-1){
pre[i] = (i < K ? 0 : pre[i-K]) + 2 * p[i];
}
cur = 0;
DEC(i,N-1,0){
post[i] = (i + K >= N ? 0 : post[i+K]) + 2 * (L-p[i]);
}
//FOR(i,0,N-1){
//cout << pre[i] << ' ' << post[i] << '\n';
//}
int ans = min(pre[N-1], post[0]);
ans = min(ans, (ll)((N + K - 1) / K) * L);
FOR(i,0,N-1){
ans = min(ans, pre[i] + ((N - i - 1 + K - 1) / K) * L);
ans = min(ans, post[i] + ((i + K - 1) / K) * L);
}
FOR(i,0,N-2) FOR(j,i+1,N-1){
ans = min(ans, pre[i] + post[j] + ((j - i - 1 + K - 1) / K) * L);
}
//ans = min(ans, (pre[i] + post[i+1]));
return ans;
}
