#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define debug(x) cerr << #x << " " << x << "\n"
#define debug_with_space(x) cerr << #x << " " << x << " "
#include "boxes.h"
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef pair <ll, ll> pii;
typedef pair <ll, pii> piii;
typedef tree <pii, null_type, less <pii>, rb_tree_tag, tree_order_statistics_node_update> OST;
const ll NMAX = 10000001;
const ll INF = (1LL << 60);
const ll MOD = 1000000007;
const ll BLOCK = 101;
const ll nr_of_bits = 35;
ll s1[NMAX], s2[NMAX];
ll delivery(int N, int K, int L, int p[]){
for(int i = 1; i <= N; i++){
if(i >= K){
s1[i] = s1[i - K] + min(p[i - 1] * 2, L);
}else{
s1[i] = min(p[i - 1] * 2, L);
}
}
for(int i = N; i >= 1; i--){
if(i <= N - K + 1){
s2[i] = s2[i + K] + min((L - p[i - 1]) * 2, L);
}else{
s2[i] = min((L - p[i - 1]) * 2, L);
}
}
ll maxim = INF;
for(int i = 0; i <= N; i++){
maxim = min(maxim, s1[i] + s2[i + 1]);
}
return maxim;
}
