#include "boxes.h"
#include <cassert>
#include <iostream>
#include <vector>
#include <algorithm>
#define ll long long
#define ff first
#define ss second
#define ln "\n"
using namespace std;
vector<ll> pos;
ll n, k, l;
long long delivery(int N, int K, int L, int p[]) {
n=N; k=K; l=L;
pos.resize(n);
for (ll i=0; i<n; i++){
pos[i] = p[i];
}
vector<ll> cl(n), acl(n);
for (ll i=0; i<n; i++){
cl[i] = pos[i]*2;
if (i>=k) cl[i]+=cl[i-k];
}
for (ll i=n-1; i>=0; i--){
acl[i]=(l-pos[i])*2;
if (i+k<n) acl[i]+=acl[i+k];
}
ll ans=acl[0];
for (ll i=0; i<n; i++){
ll res = cl[i];
if (i+1<n) res+=acl[i];
ans=min(ans, res);
}
for (ll i=k; i<=n; i++){
ll res=l;
if (i-k-1>=0) res+=cl[i-k-1];
if (i<n) res+=acl[i];
ans=min(ans, res);
}
return ans;
}
