#include "boxes.h"
#include "bits/stdc++.h"
using namespace std;
using ll = long long;
long long delivery(int N, int K, int L, int p[]) {
int pos = 0;
while(p[pos] == 0 && pos < N)
pos++;
if(pos == N)
return 0;
ll ans = 1e18;
//ll temp = 0;
int t_pos = pos;
int take = 0;
while(t_pos < N && p[t_pos] <= L / 2)
{
take++;
t_pos++;
}
int oldtake = take;
// Either give some souvenirs from other half or stop.
//Begin with left side
// Don't go to other half
int r_pos = N - 1;
ll toadd = 0;
ll last_l = t_pos - 1;
while(last_l >= 0)
{
toadd += p[last_l] * 2LL;
last_l -= K;
}
ll last_r = t_pos;
while(last_r < N)
{
toadd += (L - p[last_r]) * 2LL;
last_r += K;
}
//cout << temp << " " << toadd << " " << p[r_pos] << " " << r_pos << "\n";
ans = min(ans, toadd);
// Go to other half
toadd = 0;
take = oldtake;
while(take < K && t_pos < N)
{
t_pos++;
take++;
}
last_l = t_pos - 1;
while(last_l >= 0)
{
toadd += p[last_l] * 2LL;
last_l -= K;
}
last_r = t_pos;
while(last_r < N)
{
toadd += (L - p[last_r]) * 2LL;
last_r += K;
}
//cout << temp << " " << toadd << " " << t_pos << " " << p[t_pos] << "\n";
//cout << temp << " " << toadd << "\n";
ans = min(ans, toadd);
//Begin with right side
r_pos = N - 1;
take = 0;
//toadd = 0;
while(r_pos >= pos && p[r_pos] >= L / 2)
{
take++;
r_pos--;
}
oldtake = take;
//Begin with right side
// Don't go to other half
//l_pos = ;
toadd = 0;
last_l = r_pos;
last_r = r_pos + 1;
while(last_l >= 0)
{
toadd += p[last_l] * 2LL;
last_l -= K;
}
while(last_r < N)
{
toadd += (L - p[last_r]) * 2LL;
last_r += K;
}
//cout << temp << " " << toadd << " " << p[r_pos] << " " << r_pos << "\n";
ans = min(ans, toadd);
//int l_pos = pos;
toadd = 0;
take = oldtake;
while(r_pos >= 0 && take < K)
{
//l_pos += K;
take++;
r_pos--;
}
last_l = r_pos;
last_r = r_pos + 1;
while(last_l >= 0)
{
toadd += p[last_l] * 2LL;
last_l -= K;
}
while(last_r < N)
{
toadd += (L - p[last_r]) * 2LL;
last_r += K;
}
//cout << temp << " " << toadd << " " << p[r_pos] << " " << r_pos << "\n";
ans = min(ans, toadd);
// ans = min(ans, temp);
return ans;
}
