#include "bits/stdc++.h"
#include <vector>
using namespace std;
using ll = long long;
const int INF = 1e9;
int n;
int a[5005];
vector<vector<int>> p1, p2;
void compute_p(vector<vector<int>>& p) {
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
p[i][j] = p[i][j] + p[i][j - 1] + p[i - 1][j] - p[i - 1][j - 1];
}
}
}
int get_p(vector<vector<int>> p, int l1, int r1, int l2, int r2) {
return p[r1][r2] - p[l1 - 1][r2] - p[r1][l2 - 1] + p[l1 - 1][l2 - 1];
}
int main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> a[i];
}
p1 = vector<vector<int>>(n + 5, vector<int>(n + 5, 0));
p2 = vector<vector<int>>(n + 5, vector<int>(n + 5, 0));
vector<int> dp(n + 5, INF);
for (int i = 1; i <= n; i++) {
for (int j = i + 1; j <= n; j++) {
if (a[i] > a[j]) {
++p1[a[i]][a[j]];
}
else if (a[i] < a[j]) {
++p2[a[i]][a[j]];
}
}
}
// for (int i = 1; i <= n; i++) {
// for (int j = 1; j <= n; j++) {
// cout << p1[i][j] << " \n"[j == n];
// }
// }
// cout << "\n";
// for (int i = 1; i <= n; i++) {
// for (int j = 1; j <= n; j++) {
// cout << p2[i][j] << " \n"[j == n];
// }
// }
compute_p(p1);
compute_p(p2);
// cout << "===\n";
// for (int i = 1; i <= n; i++) {
// for (int j = 1; j <= n; j++) {
// cout << p1[i][j] << " \n"[j == n];
// }
// }
// cout << "\n";
// for (int i = 1; i <= n; i++) {
// for (int j = 1; j <= n; j++) {
// cout << p2[i][j] << " \n"[j == n];
// }
// }
dp[0] = 0;
for (int i = 1; i <= n; i++) {
{
int cost2 = get_p(p2, 1, i, 1, i);
dp[i] = min(dp[i], cost2);
}
for (int j = 1; j < i; j++) {
int cost1 = get_p(p1, j + 1, i, 1, j);
int cost2 = get_p(p2, j + 1, i, j + 1, i);
dp[i] = min(dp[i], cost1 + cost2 + dp[j]);
}
}
cout << dp[n] << "\n";
}
