#include <bits/stdc++.h>
using namespace std;
#define int long long
#define FOR(i,s,e) for(int i = s; i <= (int)e; ++i)
#define DEC(i,s,e) for(int i = s; i >= (int)e; --i)
#define IAMSPEED ios_base::sync_with_stdio(false); cin.tie(0);
#ifdef LOCAL
#define db(x) cerr << #x << "=" << x << "\n"
#define db2(x, y) cerr << #x << "=" << x << " , " << #y << "=" << y << "\n"
#define db3(a,b,c) cerr<<#a<<"="<<a<<","<<#b<<"="<<b<<","<<#c<<"="<<c<<"\n"
#define dbv(v) cerr << #v << ":"; for (auto ite : v) cerr << ite << ' '; cerr <<"\n"
#define dbvp(v) cerr << #v << ":"; for (auto ite : v) cerr << "{" << ite.f << ',' << ite.s << "} "; cerr << "\n"
#define dba(a,ss,ee) cerr << #a << ":"; FOR(ite,ss,ee) cerr << a[ite] << ' '; cerr << "\n"
#define reach cerr << "LINE: " << __LINE__ << "\n";
#else
#define reach
#define db(x)
#define db2(x,y)
#define db3(a,b,c)
#define dbv(v)
#define dbvp(v)
#define dba(a,ss,ee)
#endif
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define pb push_back
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define f first
#define s second
#define g0(x) get<0>(x)
#define g1(x) get<1>(x)
#define g2(x) get<2>(x)
#define g3(x) get<3>(x)
typedef pair <int, int> pi;
typedef tuple<int,int,int> ti3;
typedef tuple<int,int,int,int> ti4;
int rand(int a, int b) { return a + rng() % (b-a+1); }
const int MOD = 1e9 + 7;
const int inf = (int)1e9 + 500;
const long long oo = (long long)1e18 + 500;
template <typename T> bool chmax(T& a, const T b) { return a<b ? a = b, 1 : 0; }
template <typename T> bool chmin(T& a, const T b) { return a>b ? a = b, 1 : 0; }
const int MAXN = 10000005;
int ans=oo;
int pref[MAXN]; // cost for the first i things to all be routed like 0->x->0
int suf[MAXN]; // cost for the last i things to all be routed like 0->y->0
int A[MAXN];
long long delivery(int32_t n, int32_t k, int32_t l, int32_t p[]) {
db3(n,k,l);
FOR(i,1,n) {
A[i] = p[i-1];
}
FOR(i,1,n) {
pref[i] = pref[i-1];
if(i % k == 0)pref[i] += 2*A[i];
}
int len = 0;
DEC(i,n,1) {
suf[i] = suf[i+1];
++len;
if(len % k == 0)suf[i]+=2*(l-A[i]);
}
dba(pref,1,n);
dba(suf,1,n);
FOR(st,1,n-k+1) { // position of the start of the range i am looping
int en=st+k-1; // ending position of the range that i am looping.
db2(st,en);
int fi=st-1;
int sum = 0;
sum += pref[fi];
if(fi % k != 0)sum += 2*A[fi];
int se=en+1;
sum += suf[se];
db(sum);
int len=(n-se+1);
if(len % k!=0)sum+=2*(l-A[se]);
sum += l;
db(sum);
chmin(ans, sum);
}
db(ans);
FOR(i,0,n) {
int sum = 0;
sum += pref[i];
db2(sum,2*A[i]);
if(i%k!=0)sum+=2*A[i];
sum += suf[i+1];
int len=(n-(i+1)+1);
if(i!=n) {
if(len % k != 0)sum+=2*(l-A[i+1]);
}
db2(sum,2*(l-A[i+1]));
chmin(ans, sum);
}
db(ans);
return ans;
}
