// #pragma GCC target ("avx2")
// #pragma GCC optimization ("O3")
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
const int MOD = 1e9 + 7;
ll binpow(ll a, ll p, int mod = MOD) {
ll res = 1;
while (p) {
if (p & 1) {
(res *= a) %= mod;
}
p >>= 1;
(a *= a) %= mod;
}
return res;
}
ll gcd(ll a, ll b) {
return b == 0 ? a : gcd(b, a % b);
}
const int N = 5005;
int dist[N][N];
int nxt[N][N], prv[N][N];
int dp[N];
int a[N], pos[N];
void solve() {
int n;
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> a[i];
pos[a[i]] = i;
}
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
if (pos[j] > pos[i]) {
nxt[i][j] = 1;
}
if (pos[j] < pos[i]) {
prv[i][j] = 1;
}
}
for (int j = 1; j <= n; j++) {
nxt[i][j] += nxt[i][j - 1];
prv[i][j] += prv[i][j - 1];
}
}
for (int i = 1; i <= n; i++) {
dist[i][i] = prv[i][n] - prv[i][i];
}
for (int len = 2; len <= n; len++) {
for (int i = 1; i <= n - len + 1; i++) {
int j = i + len - 1;
dist[i][j] = dist[i][j - 1] + (prv[j][n] - prv[j][i - 1]) - (nxt[j][j - 1] - nxt[j][i - 1]);
}
}
for (int i = 1; i <= n; i++) {
dp[i] = 1e9;
for (int j = 0; j < i; j++) {
dp[i] = min(dp[i], dp[j] + dist[j + 1][i]);
}
}
cout << dp[n] << '\n';
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int T = 1;
// cin >> T;
for (int tc = 1; tc <= T; tc++) {
// cout << "Case #" << tc << ": ";
solve();
}
return 0;
}
