#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
template<class T> using oset =
tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define ll long long
#define ld long double
#define ar array
#define vi vector<int>
#define vii vector<vector<int>>
#define pii pair<int, int>
#define pb push_back
#define all(x) x.begin(), x.end()
#define f first
#define s second
#define endl "\n"
const int MOD = 1e9+7;
const int inf = 1e9;
const ll linf = 1e18;
const int d4i[4]={-1, 0, 1, 0}, d4j[4]={0, 1, 0, -1};
const int d8i[8]={-1, -1, 0, 1, 1, 1, 0, -1}, d8j[8]={0, 1, 1, 1, 0, -1, -1, -1};
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
// -------------------------------------------------- Main Code --------------------------------------------------
struct bits {
int n;
vi tree;
bits(int N) {n = N+5; tree = vi(n+5);}
void update(int idx, int val) { for (idx; idx <= n; idx += (idx&-idx)) tree[idx] += val; }
int sum(int idx) { int ans = 0; for (idx; idx; idx -= (idx&-idx)) ans += tree[idx]; return ans; }
int query(int l, int r) { return sum(r)-sum(l-1); }
};
const int N = 5001;
int a[N], pos[N], dp[N];
void sol() {
int n; cin >> n;
for (int i = 1; i <= n; i++) cin >> a[i], pos[a[i]] = i;
for (int i = 1; i <= n; i++) dp[i] = inf;
bits smaller(n+1);
vi small(n+1);
for (int i = 1; i <= n; i++) {
smaller.update(pos[i], 1);
int cost = 0;
bits bigger(n);
for (int j = i; j >= 1; j--) {
// cost = (elements < j after pos[j]) + (elements > j && <= i after pos[j])
if (i == j) small[i] = smaller.query(pos[j]+1, n);
cost += small[j];
cost += bigger.query(pos[j]+1, n);
cost -= bigger.query(1, pos[j]-1);
dp[i] = min(dp[j-1]+cost, dp[i]);
bigger.update(pos[j], 1);
}
}
cout << dp[n] << endl;
}
int main () {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int t = 1;
// cin >> t;
while (t--) {
sol();
}
return 0;
}
