/**
* In the name of Allah
* We are nothing and you're everything
* Ya Muhammad!
**/
#include <bits/stdc++.h>
#include "boxes.h"
using namespace std;
using ll = long long;
using ull = uint64_t;
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
//#define int long long
const char nl = '\n';
long long delivery(int n, int k, int L, int p[]) {
ll res = 0;
vector<ll> l;
for (int i = 0; i < n; ++i) {
if (p[i]>L/2)break;
if (i+1 <= k)l.push_back(p[i]*2);
else l.push_back(l[sz(l)-k]+p[i]*2);
res = l.back();
}
ll back = 0;
vector<ll> r;
for (int i = n-1; i >= 0; --i) {
if (p[i] <= L/2)break;
if (n-i <= k)r.push_back((L-p[i])*2);
else r.push_back(r[sz(r)-k]+(L-p[i])*2);
back = r.back();
}
res += back;
int start = 0;
while (start < sz(l)) {
int len1 = sz(l)-start;
if (len1>=k){start++;continue;}
if (sz(r)<=k-len1)
res = min(res, (start>0?l[start-1]:0ll)+L);
else {
res = min(res, (start>0?l[start-1]:0ll)+L+r[sz(r)-k+len1-1]);
}
start += 1;
}
return res;
}
