#include <iostream>
#include <vector>
#include <algorithm>
#include <numeric>
#include <queue>
using namespace std;
int n;
int const inf = 1e9;
vector<int>a, idx;
vector<int>cost;
int total_cost;
vector<vector<int>>left_num, right_num;
void precalc_cost(){
left_num.resize(n+1);
right_num.resize(n+1);
for(int i = 1; i <= n; i++){
for(int j = i+1; j <=n; j++){
left_num[a[j]].push_back(a[i]);
}
}
for(int i = n; i >= 1; i--){
for(int j = i-1; j >= 1; j--){
right_num[a[j]].push_back(a[i]);
}
}
for(int i = 1; i <= n; i++){
sort(left_num[i].begin(), left_num[i].end());
sort(right_num[i].begin(), right_num[i].end());
}
}
int query(vector<int> &v, int l, int r){
if(l > r)
return 0;
//numbers less than or equal to r
int num_r = lower_bound(v.begin(), v.end(), r+1)-v.begin();
//numbers less than l
int num_l = lower_bound(v.begin(), v.end(),l)-v.begin();
return num_r-num_l;
}
int query_left(int num, int l, int r){
return query(left_num[num], l, r);
}
int query_right(int num, int l, int r){
return query(right_num[num], l, r);
}
void calculate_cost(int val){
vector<int>p(n+1);
// iota(p.begin(), p.end(), 0);
// reverse(p.begin()+1, p.begin()+val+1);
// for(int i = val; i >= 1; i--){
// int inv = 0;
// for(int j = i+1; j <= n; j++){
// if((p[i] < p[j] && idx[i] > idx[j]) ||
// (p[i] > p[j] && idx[i] < idx[j]))
// inv++;
// }
// cost.push_back(inv);
// total_cost += inv;
// }
iota(p.begin(), p.end(), 0);
reverse(p.begin()+1, p.begin()+val+1);
int inv = 0;
for(int i = val; i >= 1; i--){
inv += query_left(i, val+1, n);
inv += query_right(i, i+1, val);
cost.push_back(inv);
total_cost += inv;
}
}
int main(){
cin >> n;
a.resize(n+1);
idx.resize(n+1);
vector<int>dp(n+1, inf);
for(int i = 1; i <= n; i++){
cin >> a[i];
idx[a[i]] = i;
}
precalc_cost();
dp[0] = 0;
for(int i = 1; i <= n; i++){
calculate_cost(i);
for(int j = 1; j <= i; j++){
// dp[i] = min(dp[i], dp[j-1] + total_cost);
// total_cost -= cost.back();
dp[i] = min(dp[i], dp[j-1] + cost.back());
cost.pop_back();
}
}
cout << dp[n] << '\n';
return 0;
}
