#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef vector<ll> vll;
typedef vector <pair<ll, ll>> vp;
typedef pair<ll, ll> pll;
typedef map <ll, ll> mll;
typedef set <ll> sll;
#define pb push_back
#define ff first
#define ss second
#define all(x) (x).begin(), (x).end()
#define print(x) for (auto i : x) cout << i << ' '; cout << '\n';
#define FastIO ios_base::sync_with_stdio(false); cin.tie(NULL);
const ll maxn = 5e3+5;
const ll mod = 1e9+7;
const ll inf = 2e18;
ll pw(ll a, ll b, ll M = mod) {ll ans = 1; for (; b; a = ((a * a) % M), b >>= 1) if (b & 1) ans = (ans * a) % M; return ans;}
ll n, a[maxn], ind[maxn], inv[maxn], cnt[maxn][maxn], dp[maxn], cnt2[maxn][maxn], sm[maxn];
int main() {
FastIO
cin >> n;
for (ll i = 1; i <= n; i++) {
cin >> a[i];
ind[a[i]] = i;
for (ll j = 1; j < i; j++) {
if (a[j] < a[i]) {
inv[a[i]]++;
}
}
sm[a[i]] = a[i]-1-inv[a[i]];
}
for (ll i = 1; i <= n; i++) {
cnt2[i][i] = ind[i]-1-inv[i];
for (ll j = i+1; j <= n; j++) {
cnt2[i][j] = cnt2[i][j-1] + ind[j]-1-inv[j] - sm[j];
}
for (ll k = 1; k < ind[i]; k++) {
if (a[k] > i) sm[a[k]]--;
}
}
for (ll i = 1; i <= n; i++) {
for (ll j = i+1; j <= n; j++) {
cnt[i][j] = cnt[i][j-1] + inv[j];
}
for (ll k = ind[i]+1; k <= n; k++) {
if (a[k] > i) inv[a[k]]--;
}
}
for (ll i = n-1; i > 0; i--) {
dp[i] = inf;
for (ll j = i; j <= n; j++) {
dp[i] = min(dp[i], cnt[i][j] + cnt2[i][j] + dp[j+1]);
}
}
cout << dp[1] << '\n';
return 0;
}
