#include <fstream>
#include <iostream>
#include <algorithm>
#include <cmath>

using namespace std;

ifstream in("barman.in");
ofstream out("barman.out");
int n;
int v[1205];
int sorted_v[1205];
int used[1205];
int INF = (1 << 30);

int main()
{
    in >> n;
    for(int i = 1; i <= n; i++)
    {
        in >> v[i];
        sorted_v[i] = v[i];
    }

    // Sortam doar intervalul de baza
    sort(sorted_v + 1, sorted_v + n + 1);

    int ans = INF;
    for(int start = 1; start <= n; start++)
    {
        // 1. Construim configuratia target (shiftam circular vectorul sortat)
        int target[1205];
        for(int i = 1; i <= n; i++) {
            // Formula asta roteste vectorul perfect pentru fiecare "start"
            target[i] = sorted_v[(i + start - 2) % n + 1];
        }

        // 2. Resetam marcajele pentru iteratia curenta
        for(int i = 1; i <= n; i++) {
            used[i] = 0;
        }

        int sum = 0;

        // 3. Parcurgem STRICT de la 1 la n pentru a pastra ordinea liniara
        for(int i = 1; i <= n; i++)
        {
            for(int shift = 0; i - shift >= 1 || i + shift <= n; shift++)
            {
                int j = i - shift;
                if(j >= 1 && used[j] == 0 && v[i] == target[j])
                {
                    used[j] = 1;

                    // Calculam direct costul
                    if(i != j) {
                        sum += 20 + abs(i - j);
                    }
                    break;
                }

                j = i + shift;
                if(j <= n && used[j] == 0 && v[i] == target[j])
                {
                    used[j] = 1;

                    // Calculam direct costul
                    if(i != j) {
                        sum += 20 + abs(i - j);
                    }
                    break;
                }
            }
        }

        ans = min(ans, sum);
    }

    out << ans;

    return 0;
}