#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int MAXN = 5000;
int bit1[MAXN + 1], bit2[MAXN + 1];
void update(int* bit, int i, int delta) {
for (i += 1; i <= MAXN; i += i & -i) {
bit[i] += delta;
}
}
int query(int* bit, int r) {
int res = 0;
for (r += 1; r > 0; r-= r & -r) {
res += bit[r];
}
return res;
}
int query(int* bit, int l, int r) {
return query(bit, r) - query(bit, l - 1);
}
int main() {
int n;
cin >> n;
vector<int> a(n + 1), pos(n + 1);
for (int i = 1; i <= n; ++i) {
cin >> a[i];
pos[a[i]] = i;
}
vector<int> dp(n + 1, INT_MAX);
dp[0] = 0;
for (int i = 1; i <= n; ++i) {
int inversions = 0;
for (int j = 0; j <= MAXN; ++j) {
bit1[j] = bit2[j] = 0;
}
for (int j = 1; j <= i; ++j) {
inversions += query(bit1, 1, pos[j]);
update(bit1, pos[j], +1);
}
for (int j = 0; j < i; ++j) {
cerr << i << " , " << j << " = " << inversions << "\n";
dp[i] = min(dp[i], dp[j] + inversions);
inversions -= query(bit1, pos[j + 1] + 1, n)
+ query(bit2, pos[j + 1] + 1, n);
update(bit1, pos[j + 1], -1);
inversions += query(bit1, 1, pos[j + 1]);
update(bit2, pos[j + 1], +1);
}
}
cout << dp[n] << "\n";
}
