#include <bits/stdc++.h>
#define int long long
using namespace std;
int n;
int dp[5044];
void add(vector<int>& bit, int idx, int val) {
for (int i = idx + 1; i <= (int)bit.size(); i += (i & -i))
bit[i] += val;
}
int sum(vector<int>& bit, int idx) {
int ans = 0;
for (int i = idx + 1; i > 0; i -= (i & -i))
ans += bit[i];
return ans;
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n;
vector<int> ls (n + 1);
for (int i = 1; i <= n; i++)
cin >> ls[i];
for (int i = 0; i <= n; i++)
dp[i] = 1e16;
dp[0] = 0;
for (int l = 0; l + 1 <= n; l++) {
vector<int> bit (n + 2, 0);
vector<int> pos (n + 1, 0);
/*
we used everything from 1 to l
*/
int cur = l + 1;
for (int i = 1; i <= n; i++)
if (ls[i] > l)
pos[ls[i]] = cur++;
int s = 0;
int inv = 0;
for (int r = l + 1; r <= n; r++) {
// from l + 2 to r + 1
s += pos[r];
inv += sum(bit, pos[r]);
add(bit, pos[r], 1);
//cout << "from " << l << " to " << r << " s " << s << ' ' << inv << '\n';
dp[r] = min(dp[r], dp[l] + inv + s - ((r * (r + 1) / 2) - (l * (l + 1) / 2)));
}
}
cout << dp[n] << '\n';
}
