#include <bits/stdc++.h>
#include "boxes.h"
using namespace std;
using ll = long long;
#define MAXN (1000005)
long long delivery(int N, int K, int L, int p[]) {
ll minimum = 5e18;
ll clockwise[N + 5];
memset(clockwise,0,sizeof(clockwise));
for(ll i = 0;i < N;i++){
if(i < K){
clockwise[i + 1] = 2 * p[i];
}else{
clockwise[i + 1] = clockwise[i + 1 - K] + (2 * p[i]);
}
}
ll anticlockwise[N + 5];
memset(anticlockwise,0,sizeof(anticlockwise));
for(ll i = N - 1;i >= 0;i--){
if(i >= N - K + 1){
anticlockwise[i + 1] = 2 * (L - p[i]);
}else{
anticlockwise[i + 1] = anticlockwise[i + 1 + K] + (2 * (L - p[i]));
}
}
for(ll i = 0;i <= N;i++){
minimum = min(minimum,clockwise[i] + anticlockwise[i + 1]);
}
for(ll i = 0;i <= N - K;i++){
minimum = min(minimum,clockwise[i] + anticlockwise[i + 1 + K] + L);
}
return minimum;
}
