#include <bits/stdc++.h>
using namespace std;
const int N = 5e3 + 5;
const int INF = 1e9;
int DP[N];
int H[N];
int Position[N];
int Help[N][N];
int Help2[N][N];
int Help3[N][N];
void Precalc(int n)
{
for(int i = 1; i <= n; i++) {
for(int j = 1; j < i; j++)
Help[i][j] = Help[i][j-1] + (Position[j] > Position[i]);
}
for(int i = n; i >= 1; i--) {
for(int j = i+1; j <= n; j++) {
Help2[i][j] = Help2[i][j-1] + (Position[i] > Position[j]);
}
}
}
int Find(int a, int b)
{
int sol = 0;
sol += Help[b][b-1];
sol -= Help2[b][a];
sol += (a-b) - Help2[b][a];
return sol;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
int n;
cin >> n;
for(int i = 0; i < n; i++) {
cin >> H[i];
Position[H[i]] = i;
}
Precalc(n);
for(int i = 1; i <= n; i++) {
DP[i] = INF;
int cnt = 0;
for(int j = i; j >= 1; j--) {
cnt += Find(i, j);
DP[i] = min(DP[i], DP[j-1] + cnt);
}
}
cout << DP[n] << "\n";
return 0;
}
