#include "boxes.h"
#include <bits/stdc++.h>
#define ll long long
using namespace std;
const ll maxn = 2*1e5+5, INF = 4e18+9;
ll solve(int n, int k, int B, int L, vector<int> a){
vector<int> b(1, 0), c(1, 0);
for(int i = 1; i <= n; i++){
if(a[i] <= B){
b.push_back(a[i]);
}
}
for(int i = n; i >= 1; i--){
if(a[i] > B){
c.push_back(L-a[i]);
}
}
vector<vector<ll>> sum(2, vector<ll>(k+1, 0)), pf(2, vector<ll>(k+1, 0));
for(int i = 1; i < b.size(); i++){
sum[0][i%k] += b[i]*2;
}
for(int i = 1; i < c.size(); i++){
sum[1][i%k] += c[i]*2;
}
ll ans = INF;
for(int i = 0; i < k; i++){
int j = (b.size()-1 - i + 2*k-1)%k;
ll hl = 0;
if((b.size()-1-i+2*k)%k > 0) hl = L;
ans = min(ans, sum[0][i] + sum[1][j] + hl);
}
return ans;
}
long long delivery(int N, int K, int L, int p[]) {
int n = N, k = K;
vector<int> a(n+1);
for(int i = 1; i <= n; i++){
a[i] = p[i-1];
}
ll ans = INF;
if(n%2==0){
ans = min(ans, solve(n, k, L/2, L, a));
ans = min(ans, solve(n, k, L/2-1, L, a));
}else{
ans = min(ans, solve(n, k, L/2, L, a));
}
return ans;
}
