//#pragma once
//#include "grader.cpp"
#include "boxes.h"
#include "bits/stdc++.h"
using namespace std;
long long int n,k,m,a[200005],l,r,used[200005];
long long int mi;
long long int go_from_left()
{
int num=0;
long long int otg=0;
for(int i=1;i<=n;i++)
{
num++;
if(num==k||i==n)
{
num=0;
if(a[i]<=l)otg+=a[i]*2;
else if(a[i-k+1]<=l)otg+=m;
else otg+=(m-a[i])*2;
}
}
return otg;
}
long long int go_from_right()
{
int num=0;
long long int otg=0;
for(int i=n;i>=1;i--)
{
num++;
if(num==k||i==1)
{
num=0;
if(a[i]>=r)otg+=(m-a[i])*2;
else if(a[i+k-1]>=r)otg+=m;
else otg+=a[i]*2;
}
}
return otg;
}
long long int delivery(int N, int K, int L, int p[])
{
n=N;
k=K;
m=L;
for(int i=0;i<n;i++)
{
a[i+1]=p[i];
}
l=(m-1)/2;
r=(m+1)/2;
mi=min(go_from_left(),go_from_right());
cout<<mi<<endl;
return mi;
}
