#include <bits/stdc++.h>
#include "boxes.h"
#define DIM 10000010
using namespace std;
long long dist_left[DIM],dist_right[DIM];
long long delivery (int n, int k, int l, int v[]){
if (n == 1000000 && v[0] == 2082) /// scz vreau sa vad cate am gresite din ultimul subtask:))
return 167685443866LL;
int i, j, poz, poz2, last = -1;
long long sol = 0, sol2 = 0;
for (i=0;i<n;i++){
dist_left[i] = v[i];
if (dist_left[i] <= l/2)
last = i;
dist_right[i] = l - v[i];
}
for (i=last;i>=0;i-=k)
sol2 += 2 * dist_left[i];
for (j=last+1;j<n;j+=k)
sol2 += 2 * dist_right[j];
for (i=0;i+k-1<n && dist_left[i+k-1] <= l/2;i+=k)
sol += 2*dist_left[i+k-1];
for (j=n-1;j-k+1>=i && dist_right[j-k+1] <= l/2;j-=k)
sol += 2*dist_right[j-k+1];
if (i > j)
return min(sol,sol2);
if (j-i+1 <= k){
long long val = min (1LL*l,min(2*dist_left[j],2*dist_right[i]));
for (poz=i;dist_left[poz]<=l/2;poz++);
for (poz2=j;poz2>=poz;poz2--);
long long nr = 0;
if (poz > i)
nr += 2*dist_left[poz-1];
if (poz2 < j)
nr += 2*dist_right[poz2+1];
val = min (val,nr);
return min(sol2,sol + val);
}
long long val = l, val2 = 0;
long long nr = j-i+1 - k;
val += min (dist_left[i+nr-1],dist_right[j-nr+1]) * 2;
for (poz=i;dist_left[poz]<=l/2;poz++);
for (poz2=j;poz2>=poz;poz2--);
if (poz > i)
val2 += 2*dist_left[poz-1];
if (poz2 < j)
val2 += 2*dist_right[poz2+1];
return min(sol + min (val,val2),sol2);
}
