#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <cmath>
#include <vector>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <queue>
#include <ctime>
#include <cassert>
#include <complex>
#include <string>
#include <cstring>
#include <chrono>
#include <random>
#include <bitset>
#include <fstream>
#include <array>
#include <functional>
#include <stack>
#include <memory>
#ifdef LOCAL
#define _GLIBCXX_DEBUG
#endif
using namespace std;
#define int long long
#define app push_back
#define all(x) x.begin(), x.end()
#ifdef LOCAL
#define debug(...) [](auto...a){ ((cout << a << ' '), ...) << endl; }(#__VA_ARGS__, ":", __VA_ARGS__)
#define debugv(v) do { cout << #v << ": "; for (auto x : v) cout << x << ' '; cout << endl; } while(0)
#else
#define debug(...)
#define debugv(v)
#endif
int32_t main() {
cin.tie(0);ios_base::sync_with_stdio(0);
int n;
cin >> n;
vector <int> h(n), q(n + 1);
for (int i = 0; i < n; ++i) {
cin >> h[i];
h[i]--;
q[h[i]]=i;
}
vector <vector <int> > pre(n + 1, vector <int> (n + 1));
for (int x = 0; x < n; ++x) {
for (int y = 0; y < x; ++y) {
if (q[x] < q[y]) {
pre[x + 1][y + 1]++;
}
}
}
for (int i = 0; i < n; ++i) {
for (int j = 0; j < n; ++j) {
pre[i + 1][j + 1] += pre[i + 1][j] + pre[i][j + 1] - pre[i][j];
}
}
auto inv = [&] (int y1, int y2, int x1, int x2) {
return pre[x2][y2] - pre[x1][y2] - pre[x2][y1] + pre[x1][y1];
};
auto c2 = [&] (int k) {
return k * (k - 1) / 2;
};
vector <int> dp(n + 1, n * n);
dp.front() = 0;
for (int l = 0; l < n; ++l) {
for (int r = l + 1; r <= n; ++r) {
dp[r] = min(dp[r], dp[l] + inv(0, l, l, r) + (c2(r - l) - inv(l, r, l, r)));
}
}
cout << dp.back() << '\n';
}
