#include <bits/stdc++.h>
using namespace std;
#define forsn(i, s, n) for (int i = int(s); i < int(n); i++)
#define forn(i, n) forsn(i, 0, n)
#define dforsn(i, s, n) for (int i = int(n) - 1; i >= int(s); i--)
#define dforn(i, n) dforsn(i, 0, n)
#define sz(x) int(x.size())
#define all(x) begin(x), end(x)
using ll = long long;
using ld = long double;
using vi = vector<int>;
using vb = vector<bool>;
using vll = vector<ll>;
using ii = pair<int, int>;
using iii = tuple<int, int, int>;
#define fst first
#define snd second
#define pb push_back
#define eb emplace_back
const ll INF = 1e18;
int main() {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int n;
cin >> n;
vi h(n);
forn(i, n) cin >> h[i], --h[i];
vi pos(n);
forn(i, n) pos[h[i]] = i;
vll dp(n + 1, INF);
dp[0] = 0LL;
vector<vi> pref(n, vi(n + 1));
forn(i, n) forn(j, n) {
pref[i][j + 1] = pref[i][j] + (pos[j] < pos[i]);
}
vector<vi> pref2(n + 1, vi(n));
forn(i, n) forn(j, n) {
pref2[i + 1][j] = pref2[i][j] + (pos[j] < pos[i]);
}
forsn(i, 1, n + 1) {
ll cost = 0LL;
dforn(j, i) {
cost += pref2[i][j] - pref2[j][j];
cost += pref[j][n] - pref[j][j];
cost -= pref[j][i] - pref[j][j];
dp[i] = min(dp[i], dp[j] + cost);
}
}
cout << dp[n] << '\n';
return 0;
}
