#include <bits/stdc++.h>
#define pb emplace_back
#define All(x) x.begin(), x.end()
using namespace std;
#define debug(args...) kout("[ " + string(#args) + " ]", args)
void kout() { cerr << endl; }
template <class T, class ...U> void kout(T a, U ...b) { cerr << a << ' ',kout(b...); }
template <class T> void pary(T L, T R) { while (L != R) cerr << *L << " \n"[++L==R]; }
const int MAXN = 17;
int N;
int ans;
vector <int> a, c;
vector <int> ord;
inline int lb(int a) {
return a &- a;
}
void init() {
a.resize(1<<N);
c.resize(1<<N);
int now = 0; ord.pb(0);
for (int i = 1; i < (1<<N); i++) {
now ^= lb(i);
ord.pb(now);
}
}
int cnt() {
int s = 0;
for (int i = 0; i < (1<<N); i++) {
for (int j = i+1; j < (1<<N); j++) {
s += c[i] > c[j];
}
}
return s;
}
signed main() {
ios_base::sync_with_stdio(0), cin.tie(0);
cin >> N;
init();
for (int i = 0; i < (1<<N); i++)
cin >> a[i], c[a[i]] = i;
ans = cnt();
for (int j = 0; j < N; j++) {
for (int id : ord) {
for (int i = 0; i < (1<<N); i++)
c[i] ^= id;
ans = min(ans, cnt());
}
for (int i = 0; i < (1<<N); i++) {
c[i] = (1<<(N-1)) * (c[i] & 1) + c[i] / 2;
}
}
cout << ans << '\n';
return 0;
}
