#ifdef LOCAL
#include "/home/bgopc/template/pch.hpp"
#endif
#include <bits/stdc++.h>
using namespace std;
// * No One Dies a Virgin, Life Fucks Us All
typedef long long ll;
#define nl '\n'
#define ff first
#define ss second
#define pb push_back
#define sik(x) {cout << x << nl; return;}
constexpr ll maxn = 5005, mod = 1e9 + 7, inf = 1e9+10, SQ = 450, LG = 20;
typedef pair<int, int> pii;
int n, g[maxn], dp[maxn], fen[2][maxn], in[maxn][maxn], out[maxn][maxn];
inline void add(int t, int p) {
for (; p <= n ; p += p & -p) fen[t][p] ++;
}
inline int get(int t, int p) {
int res = 0;
for (; p ; p -= p & -p) res += fen[t][p];
return res;
}
int32_t main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n;
for (int i = 1, h ; i <= n ; i ++) {
cin >> h;
g[h] = i;
dp[i] = inf;
}
dp[0] = 0;
for (int l = 1 ; l <= n ; l ++) {
fill(fen[0], fen[0] + n + 1, 0);
for (int r = l ; r <= n ; r ++) {
in[l][r] = in[l][r - 1] + get(0, g[r]);
out[l][r] = out[l][r - 1] + l - 1 - get(1, g[r]);
add(0, g[r]);
}
add(1, g[l]);
}
for (int i = 1 ; i <= n ; i ++) {
for (int j = 0 ; j < i ; j ++) dp[i] = min(dp[i], dp[j] + in[j + 1][i] + out[j + 1][i]);
}
cout << dp[n] << nl;
}
