#include <bits/stdc++.h>
#include "boxes.h"
using namespace std;
#define F first
#define S second
#define FOR(i,a,b) for (auto i = (a); i <= (b); ++i)
#define NFOR(i,a,b) for(auto i = (a); i >= (b); --i)
#define all(x) (x).begin(), (x).end()
#define sz(x) int(x.size())
#define mp(i,a) make_pair(i,a)
#define pb(a) push_back(a)
#define bit(x,b) (x&(1LL<<b))
typedef int lli;
typedef pair <lli,lli> ii;
typedef pair <lli,ii> iii;
typedef vector <lli> vi;
int arr[10000000],arr1[10000000],ans=0;
long long delivery(int N, int K, int L, int p[])
{
int n,k,l;
n=N;
k=K;
l=L;
for(int i=0;i<n;++i)
{
arr[i]=p[i]*2+((i-k>=0)?arr[i-k]:0);
}
for(int i=n-1;i>=0;--i)
arr1[i]=(l-p[i])*2+((i+k<=n-1)?arr1[i+k]:0);
ans=min(arr[n-1],arr1[0]);
for(int i=0;i<n-1;++i)
ans=min(ans,arr[i]+arr1[i+1]);
for(int i=0;i<=n;++i)
ans=min(ans,((i>0)?arr[i-1]:0)+l+((n-i-k>0)?arr1[(n)-(n-k-i)]:0));
return(ans);
}
