#include <bits/stdc++.h>
using namespace std;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int n;
cin >> n;
vector<int> a(n);
for (auto &x : a) cin >> x;
vector<int> pos(n + 1);
for (int i = 0; i < n; i++) pos[a[i]] = i;
vector<int> b = a;
sort(b.begin(), b.end());
long long ans = LLONG_MAX;
do {
bool ok = true;
for (int i = 0; i + 1 < n; i++) {
if (!(b[i] < b[i + 1] + 2)) {
ok = false;
break;
}
}
if (!ok) continue;
vector<int> m(n);
for (int i = 0; i < n; i++) m[i] = pos[b[i]];
long long e = 0;
for (int i = 0; i < n; i++) {
for (int j = i + 1; j < n; j++) {
if (m[i] > m[j]) e++;
}
}
ans = min(ans, e);
} while (next_permutation(b.begin(), b.end()));
cout << ans;
}
