//#pragma GCC optimize ("Ofast")
//#pragma GCC optimize ("unroll-loops")
//#pragma GCC target ("avx2")
#include <iostream>
#include <cmath>
#include <algorithm>
#include <stdio.h>
#include <cstdint>
#include <cstring>
#include <string>
#include <cstdlib>
#include <vector>
#include <bitset>
#include <map>
#include <queue>
#include <ctime>
#include <stack>
#include <set>
#include <list>
#include <random>
#include <deque>
#include <functional>
#include <iomanip>
#include <sstream>
#include <fstream>
#include <complex>
#include <numeric>
#include <cassert>
#include <array>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <thread>
typedef long long ll;
typedef long double ld;
#define el '\n'
#define ff first
#define ss second
#define pb push_back
#define pf push_front
#define popb pop_back
#define popf pop_front
#define point pair <ll, ll>
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
using namespace std;
mt19937_64 rnd(time(0));
const ll INF = 1e18 + 10;
const ll inf = 1e9 + 10;
const ll N = 5e3 + 10;
const ll mod = 1e9 + 7;
const ll K = 400;
const ll LOG = 25;
ll cost[N][N], dp[N], h[N], fen[N], invH[N];
void upd(ll v) {
for (; v < N; v = (v | (v + 1)))
fen[v] += 1;
}
ll get(ll v) {
ll res = 0;
for (; v >= 0; v = (v & (v + 1)) - 1)
res += fen[v];
return res;
}
void solve() {
ll n;
cin >> n;
for (ll i = 1; i <= n; i++)
cin >> h[i], invH[h[i]] = i;
for (ll l = 1; l <= n; l++) {
vector <ll> pos(n + 1), suff(n + 2);
for (ll i = 1; i < l; i++)
suff[invH[i]]++;
for (ll i = n; i >= 1; i--)
suff[i] += suff[i + 1];
for (ll i = l; i <= n; i++)
pos[i] = invH[i] + suff[invH[i]];
for (ll i = 0; i < N; i++)
fen[i] = 0;
for (ll r = l; r <= n; r++) {
cost[l][r] = cost[l][r - 1] + (pos[r] - l) - (get(n) - get(pos[r]));
upd(pos[r]);
}
}
for (ll i = 1; i <= n; i++) {
dp[i] = INF;
for (ll j = 0; j < i; j++)
dp[i] = min(dp[i], dp[j] + cost[j + 1][i]);
}
cout << dp[n] << el;
return;
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
ll tests = 1;
//cin >> tests;
while (tests--)
solve();
return 0;
}
/*
*/
