#include "boxes.h"
#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
const int maxn = 1e7 + 20;
ll dp[maxn] , pd[maxn];
int a[maxn] , deq[maxn] , s , t;
long long delivery(int n, int k, int L, int p[])
{
for(int i = 1; i <= n; i++)
a[i] = p[i - 1];
s = t = 0;
deq[t++] = 0;
for(int i = 1; i <= n; i++)
{
dp[i] = dp[deq[s]] + a[i] + min(a[i] , L - a[i]);
while(t != s && dp[deq[t - 1]] >= dp[i])
t--;
deq[t++] = i;
if(deq[s] <= i - k)
s++;
}
s = t = 0;
deq[t++] = n + 1;
for(int i = n; i >= 1; i--)
{
pd[i] = pd[deq[s]] + L - a[i] + min(a[i] , L - a[i]);
while(t != s && pd[deq[t - 1]] >= pd[i])
t--;
deq[t++] = i;
if(deq[s] >= i + k)
s++;
}
ll res = 1e18;
for(int i = 0; i <= n; i++)
res = min(res , dp[i] + pd[i + 1]);
return res;
}
