#include <bits/stdc++.h>
using namespace std;
#define int long long
int32_t main()
{
cin.tie(0)->sync_with_stdio(0);
int n;
cin >> n;
vector<int> p(n + 1), pr(n + 1);
for(int i = 1; i <= n; i++) {
cin >> p[i];
pr[p[i]] = i;
}
vector inv(n + 1, vector<int>(n + 1));
for(int i = 1; i <= n; i++) {
for(int j = 1; j <= n; j++) {
inv[i][j] = inv[i][j - 1] + inv[i - 1][j] - inv[i - 1][j - 1] + (i < j && pr[j] < pr[i]); // j i
}
}
auto c = [&](int l, int r) {
return (inv[r][r] - inv[l - 1][r] - inv[r][l - 1] + inv[l - 1][l - 1]);
};
auto C2 = [&](int x) {
return x * (x - 1) / 2;
};
const int oo = 1e18;
vector<int> dp(n + 1, oo);
dp[0] = 0;
for(int i = 1; i <= n; i++) {
dp[i] = C2(i) - c(1, i);
for(int j = 1; j <= i; j++) {
int one = C2(i - j + 1) - c(j, i);
int two = c(1, i) - (j == 1 ? 0 : c(1, j - 1)) - c(j, i);
dp[i] = min(dp[i], dp[j - 1] + one + two);
}
}
cout << dp[n] << '\n';
}
