//------------------------------------\\
// ------------------------------ \\
// | created by Dinh Manh Hung | \\
// | tht.onepunchac168 | \\
// | THPT CHUYEN HA TINH | \\
// | HA TINH, VIET NAM | \\
// | Siuuu | \\
// ------------------------------ \\
//------------------------------------\\
#include "boxes.h"
#include <bits/stdc++.h>
using namespace std;
#define task ""
#define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
#define ldb long double
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define all(x) begin(x),end(x)
#define uniquev(v) v.resize(unique(all(v))-v.begin())
#define rep(i,a,b) for (int i=a;i<=b;i++)
#define cntbit(v) __builtin_popcountll(v)
#define gcd(a,b) __gcd(a,b)
#define lcm(a,b) ((1LL*a*b)/__gcd(a,b))
#define mask(x) (1LL<<(x))
#define readbit(x,i) ((x>>i)&1)
#define Yes cout << "Yes"
#define YES cout << "YES"
#define No cout << "No"
#define NO cout << "NO"
typedef long long ll;
typedef pair <ll,ll> ii;
typedef pair <ll,ii> iii;
typedef pair <ii,ii> iiii;
ll dx[]= {1,-1,0,0,1,-1,1,-1};
ll dy[]= {0,0,-1,1,1,-1,-1,1};
const ldb PI = acos (-1);
//const ll mod=978846151;
//const ll base=29;
const ll mod=1e9+7;
const char nl = '\n';
inline int ReadInt()
{
char co;
for (co = getchar(); co < '0' || co > '9'; co = getchar());
int xo = co - '0';
for (co = getchar(); co >= '0' && co <= '9'; co = getchar())
xo = (xo<<1) + (xo<<3) + co - '0';
return xo;
}
void WriteInt(int xo)
{
if (xo > 9)
WriteInt(xo / 10);
putchar(xo % 10 + '0');
}
// DEBUG
void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif
/* END OF TEMPLATE*/
// ================= Solution =================//
const int N=1e7+5;
ll dp[N];
long long delivery(int N, int K, int L, int p[]) {
if (K>N)
{
K=N;
}
ll res=1e18+5;
for (int i=0;i<N;i++)
{
if (i>=K)
{
dp[i]=dp[i-K]+min({L,p[i]*2,(L-p[i-K+1])*2});
}
else
{
dp[i]=min({L,p[i]*2,(L-p[0])*2});
}
if (i==N-1)
{
res=min(res,dp[i]);
}
else if (N-i-1<=K)
{
ll cost=min({L,p[N-1]*2,(L-p[i+1])*2});
res=min(res,cost+dp[i]);
}
}
return res;
}
/*
void onepunchac168();
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
file(task);
int tests;
tests=1;
//cin>>tests;
while (tests--)
{
onepunchac168();
}
}
const int N=2e5+5;
void onepunchac168()
{
}
*/
// goodbye see ya
