#include <bits/stdc++.h>
#include <experimental/random>
#include <random>
using namespace std;
using ll = long long;
using ld = long double;
const ll INF = 1e18, MOD = 998244353;
void solve();
signed main() {
#ifdef LOCAL
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
ll q = 1;
//cin >> q;
while (q--) {
solve();
}
}
void solve() {
ll n;
cin >> n;
vector<ll> a(n);
vector<ll> pos(n);
for (int i = 0; i < n; i++) {
cin >> a[i];
a[i]--;
pos[a[i]] = i;
}
vector<ll> dp(n, INF);
dp[0] = 0;
for (int i = 1; i < n; i++) {
for (int j = i; j >= 0; j--) {
vector<ll> cur(i + 1);
iota(cur.begin(), cur.end(), 0);
reverse(cur.begin() + j, cur.end());
ll cnt = 0;
if (j != 0) {
cnt = dp[j - 1];
}
for (int val = j; val <= i; val++) {
for (int t = 0; t < val; t++) {
ll p1 = pos[cur[val]];
ll p2 = pos[cur[t]];
if (p1 < p2) {
cnt++;
}
}
}
dp[i] = min(dp[i], cnt);
}
}
cout << dp[n - 1];
}
