#include <bits/stdc++.h>
using namespace std;

int main() {
    int n;
    cin >> n;
    vector<int> a(n), b(n), c(n);
    for (int i = 0; i < n; i++) cin >> a[i];
    iota(b.begin(), b.end(), 1);
    c = a;
    int cnt1 = 0;
    while (1) {
        for (int i = 0; i < n; i++) {
            if (c[i] == c[0] - 1) {
                int x = c[i];
                c.erase(c.begin() + i);
                c.insert(c.begin(), x);
                cnt1++;
                break;
            }
        }
        if (c == b) break;
        if (cnt1 == n) {
            cnt1 = 1000000000;
            break;
        }
    }
    c = a;
    int ind = n;
    int cnt2 = 0;
    while (1) {
        for (int i = 0; i < n; i++) {
            if (c[i] == ind) {
                c.erase(c.begin() + i);
                c.insert(c.begin(), ind);
                ind--;
                cnt2++;
                break;
            }
        }
        if (c == b) break;
    }
    cout << min(cnt1, cnt2) << endl;

    return 0;
}