#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
#define pb push_back
#define pii pair<ll, ll>
#define pll pair<ll, ll>
#define st first
#define nd second
#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
#define debug false
const int MAXN = 5017;
int a[MAXN + 1];
int dp[MAXN + 1];
int pos[MAXN + 1];
int pom[MAXN][MAXN];
int main () {
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int n;
cin >> n;
for (int i = 0; i < n; i ++) {
cin >> a[i];
a[i] --;
pos[a[i]] = i;
}
for (int i = 1; i <= n; i ++) {
dp[i] = INT_MAX;
}
dp[0] = 0;
for (int i = n - 2; i >= 0; i --) {
for (int j = 0; j < n; j ++) {
pom[i][j] = pom[i + 1][j] + (j <= a[i + 1]);
}
}
for (int i = 1; i <= n; i ++) {
int akt = 0;
for (int j = i - 1; j >= 0; j --) {
akt += pom[pos[j]][j] - 2 * pom[pos[j]][i] + (n - i);
dp[i] = min(dp[i], dp[j] + akt);
}
//cout << dp[i] << "\n";
}
cout << dp[n] << "\n";
return 0;
}
