#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using pll = pair<ll, ll>;
#define all(x) x.begin(), x.end()
#define pb push_back
const int MXN = 5005;
int n, inv[MXN], pos[MXN], a[MXN], dp[MXN];
int32_t main() {
cin.tie(0); cout.tie(0); ios_base::sync_with_stdio(0);
cin >> n;
for(int i=1; i<=n; i++) cin >> a[i];
for(int i=n-1; i>=1; i--) {
int lst=0;
for(int j=1; j<=n; j++)
if(a[j]>=i)
pos[a[j]] = lst++;
for(int j=i+1; j<=n; j++)
if(pos[j]<pos[i]) inv[j]++;
int cur=0;
dp[i] = 2e9;
for(int j=i; j<=n; j++) {
cur += pos[j] - inv[j];
dp[i] = min(dp[i], cur+dp[j+1]);
}
}
cout << dp[1] << '\n';
return 0;
}
