#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
struct bitr {
void resize(int n) {
t.resize(n);
sz = n;
}
void add(int i, int x) {
while (i < sz) {
t[i] += x;
i |= i + 1;
}
}
int get(int i) {
int ans = 0;
while (i > -1) {
ans += t[i];
i &= i + 1;
--i;
}
return ans;
}
int operator()(int l, int r) {
return get(r - 1) - get(l - 1);
}
private:
int sz;
vector<int> t;
};
const int MAXN = 5001;
int a[MAXN];
int ra[MAXN];
int dp_[MAXN];
int* dp = dp_ + 1;
signed main() {
int n;
cin >> n;
for (int i = 0; i < n; ++i)
cin >> a[i];
for (int i = 0; i < n; ++i)
ra[--a[i]] = i;
for (int i = 0; i < n; ++i)
dp[i] = MAXN * MAXN;
for (int i = -1; i < n; ++i) {
bitr used;
bitr nonused;
used.resize(n);
nonused.resize(n);
for (int j = i + 1; j < n; ++j) {
nonused.add(ra[j], 1);
}
int add = 0;
for (int j = i + 1; j < n; ++j) {
nonused.add(ra[j], -1);
add += nonused.get(ra[j] - 1);
add -= used(ra[j], n);
add += used.get(ra[j]);
used.add(ra[j], 1);
dp[j] = min(dp[j], dp[i] + add);
}
}
cout << dp[n - 1] << '\n';
}
