#include <iostream>
#include <algorithm>
#include <vector>
#include <utility>
using namespace std;	

int a[29], b[29], r[29], d[29];
vector<pair<int, int> > av, bv;

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	int n; cin >> n;
	for (int i = 0; i < n; i++) cin >> a[i];
	for (int i = 0; i < n; i++) {
		cin >> b[i];
		if (i % 2) swap(a[i], b[i]);
	}
	int ans = 1000000000;
	for (int i = 0; i < (1 << n); i++) {
		int t = i, c = 0;
		while (t) {
			t -= (t & (-t)); c++;
		}
		if (c != (n + 1) / 2) continue;
		av.clear(); bv.clear();
		for (int j = 0; j < n; j++) {
			if (i & (1 << j)) av.push_back(make_pair(a[j], j));
			else bv.push_back(make_pair(b[j], j));
		}
		sort(av.begin(), av.end());
		sort(bv.begin(), bv.end());
		bool f = true;
		for (int j = 0; j < n; j++) {
			if (j % 2) { r[j] = bv[j / 2].second; d[j] = bv[j / 2].first; }
			else { r[j] = av[j / 2].second; d[j] = av[j / 2].first; }
			if (j > 0 && d[j] < d[j - 1]) {
				f = false;
				break;
			}
		}
		if (!f) continue;
		int s = 0;
		for (int j = 0; j < n; j++)
			for (int k = j + 1; k < n; k++)
				if (r[j] > r[k])
					s++;
		ans = min(ans, s);
	}
	if (ans == 1000000000) cout << -1 << '\n';
	else cout << ans << '\n';
	return 0;
}	