#include <bits/stdc++.h>
#define ff(i,a,b) for(int (i) = (a); (i) <= (b); ++(i))
#define fb(i,a,b) for(int (i) = (a); (i) >= (b); --(i))
#include "boxes.h"
#define maxn 10000005
using namespace std;
typedef long long ll;
int n,k;
int niz[maxn];
int d;
set<int>s;
ll dist(int l, int r){
if(l > r)swap(l, r);
ll res = min(r - l, l + d - r);
return res;
}
ll levi[maxn];
ll desni[maxn];
long long delivery(int N, int K, int L, int p[]) {
n = N, k = K, d = L;
ff(i,1,n)niz[i] = p[i - 1];
sort(niz + 1, niz + 1 + n);
levi[0] = 0;
desni[n + 1] = 0;
ff(i,1,n){
if(k == 1 || i%k == 1){
levi[i] = levi[i - 1] + 2*niz[i];
}
else{
levi[i] = levi[i - 1] - niz[i - 1] + niz[i] - niz[i - 1] + niz[i];
}
}
fb(i,n,1){
int kol = n - i + 1;
if(kol%k == 1 || k == 1){
desni[i] = desni[i + 1] + 2*(d-niz[i]);
//cout << i << " " << desni[i] << endl;
//exit(0);
}
else{
desni[i] = desni[i + 1] - (d-niz[i + 1]) + (d-niz[i]) - (d-niz[i + 1]) + (d-niz[i]);
}
}
ll res = levi[1] + desni[2];
ff(i,0,n){
res = min(res, levi[i] + desni[i + 1]);
}
ff(i,1,n){
res = min(res, levi[i - 1] + d + desni[i + k]);
}
return res;
}
/*
int aa[maxn];
int N,K,L;
int main(){
freopen("06", "r", stdin);
cin >> N >> K >> L;
ff(i,0,N - 1)cin >> aa[i];
cout << delivery(N,K,L,aa);
return 0;
}
/*
3 2 8
1 2 5
*/
