#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define MASK(i) (1LL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
#define block_of_code if(true)
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll gcd(ll a, ll b){return __gcd(a, b);}
ll lcm(ll a, ll b){return a / gcd(a, b) * b;}
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ull mask){return __builtin_ctzll(mask);}
int logOf(ull mask){return 63 - __builtin_clzll(mask);}
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
double rngesus_d(double l, double r){
double cur = rngesus(0, MASK(60) - 1);
cur /= MASK(60) - 1;
return l + cur * (r - l);
}
template <class T1, class T2>
bool maximize(T1 &a, T2 b){
if (a < b) {a = b; return true;}
return false;
}
template <class T1, class T2>
bool minimize(T1 &a, T2 b){
if (a > b) {a = b; return true;}
return false;
}
template <class T>
void printArr(T container, string separator = " ", string finish = "\n", ostream &out = cout){
for(auto item: container) out << item << separator;
out << finish;
}
template <class T>
void remove_dup(vector<T> &a){
sort(ALL(a));
a.resize(unique(ALL(a)) - a.begin());
}
struct FenwickTree{
int n;
vector<int> a;
FenwickTree(int _n){
n = _n;
a.resize(n+1);
}
void update(int i, int v){
while(i <= n){
a[i] += v;
i += LASTBIT(i);
}
}
int get(int i){
int ans = 0;
while(i > 0){
ans += a[i];
i -= LASTBIT(i);
}
return ans;
}
};
const int N = 5005, INF = 1e9 + 69;
int n;
int a[N], p[N];
int dp[N];
int cost[N][N];
int main(void){
ios::sync_with_stdio(0);cin.tie(0); cout.tie(0);
clock_t start = clock();
cin >> n;
for(int i= 1; i<=n; ++i) cin >> a[i];
for(int i = 1; i<=n; ++i) p[a[i]] = i;
FenwickTree bit1(n);
for(int i = 1; i<=n; ++i){
FenwickTree bit2(n);
for(int j = i; j<=n; ++j){
cost[i][j] = cost[i][j-1];
cost[i][j] += (i - 1) - bit1.get(p[j]);
cost[i][j] += bit2.get(p[j]);
bit2.update(p[j], 1);
}
bit1.update(p[i], 1);
}
for(int i= 1; i<=n; ++i) dp[i] = INF;
for(int i = 0; i<n; ++i){
for(int j = i + 1; j <= n; ++j)
minimize(dp[j], dp[i] + cost[i+1][j]);
}
cout << dp[n] << "\n";
cerr << "Time elapsed: " << clock() - start << " ms\n";
return 0;
}
