#include <iostream>
#define ll long long
using namespace std;
const int N = 5e3+5;
ll n, a[N], id[N], dp[N], cnt[N][N], cost[N][N];
int main() {
ios::sync_with_stdio(0); cin.tie(0);
cin >> n;
for(int i = 1; i <= n; ++i) {
cin >> a[i];
id[a[i]] = i;
}
for(int i = 1; i <= n; ++i) {
for(int j = n; j >= 1; --j) {
cnt[i][j] = cnt[i][j+1] + (id[j] < id[i]);
}
}
for(int L = 1; L <= n; ++L) {
for(int R = L; R <= n; ++R) {
cost[L][R] = cost[L][R - 1] + cnt[R][L] - (R - L - (cnt[R][L] - cnt[R][R+1]));
}
}
for(int i = 1; i <= n; ++i) {
dp[i] = 1e15;
for(int j = 0; j < i; ++j) {
dp[i] = min(dp[i], dp[j] + cost[j+1][i]);
}
}
cout << dp[n] << endl;
}
