#include <bits/stdc++.h>
#include "boxes.h"
using namespace std;

#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)
#else
#define debug(...){}
#endif

#define ll long long
#define ld long double
#define endl '\n'
#define st first
#define nd second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define FOR(i,l,r) for(int i=(l);i<=(r);i++)
#define ROF(i,r,l) for(int i=(r);i>=(l);i--)
int inf=2000000007;
ll infl=1000000000000000007;
ll mod=1000000007;

const int N=10000007;

ll DP[N];
ll a[N];
ll L;

ll cost(int l,int r)
{
	if(l>r) return 0;
	return min({L,2*a[r],2*(L-a[l])});
}

ll delivery(int n, int k, int l,int p[])
{
	L=l;
	FOR(i,0,n-1) a[i+1]=p[i];
	FOR(i,1,n) DP[i]=infl;
	FOR(i,1,k) DP[i]=cost(1,i);
	ll ans=infl;
	for(int i=1;i<=n;i++)
	{
		if(i>=k) DP[i]=min(DP[i],DP[i-k]+cost(i-k+1,i));
		if(n-i<=k) ans=min(ans,DP[i]+cost(i+1,n));
	}
	debug(ans);
	return ans;
}