#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 delivery(int n, int k, int l,int p[])
{
	for(int i=1;i<=n;i++)
	{
		DP[i]=infl;
		for(int j=i-1;j>=max(0,i-k);j--)
		{
			DP[i]=min(DP[i],DP[j]+(ll)min({l,2*p[i-1],2*(l-p[j])}));
		}
	}
	debug(DP[n]);
	return DP[n];
}