#include<iostream>
#include<algorithm>
#include<vector>
#include<set>
using namespace std;
#define ll long long
#define pii pair<ll,ll>
#define mp make_pair
#define endl "\n"
#define out(x) cout<< #x << " = " << x << endl
#define outp(x) cout << #x << " first = " << x.first << " second = " << x.second << endl
#define inf 3e18
int n;
int arr[5005], pos[5005];
int a[5005][5005]; // 預處理，[i,i+1, ... j] 這個區間放在正確位置，會出現幾個逆序
int arev[5005][5005];
int b[5005][5005]; // 預處理，前i個自排列[舊的]，第i+1到j個為-1的遞減[新的]，舊的和新的之間會產生幾個逆序
int dp[5005];
vector<int> bit(5005);
void init(){
for (int i=1;i<=n;i++) bit[i] = 0;
}
void add(int id,int x){
for (int i=id;i<=n;i+=(i&-i)) bit[i] += x;
}
int sum(int id){
if (id==0) return 0;
int ans = 0;
for (int i=id;i>=1;i-=(i&-i)) ans += bit[i];
return ans;
}
signed main(){
ios::sync_with_stdio(false); cin.tie(0);
cin>>n;
for (int i=1;i<=n;i++) cin>>arr[i], pos[arr[i]] = i;
// precalc a
for (int i=1;i<=n;i++){
init();
for (int j=i;j<=n;j++){
a[i][j] = a[i][j-1] + sum(n) - sum(pos[j]-1);
arev[i][j] = (j-i)*(j-i+1)/2 - a[i][j];
add(pos[j],1);
}
}
// precalc b
for (int i=1;i<=n;i++){
init();
for (int z=1;z<=i;z++) add(pos[z],1);
for (int j=i+1;j<=n;j++){
b[i][j] = b[i][j-1] + i - sum(pos[j]-1);
}
}
// dp[i] = 目前看到前i個位置，逆序最小數量
for (int i=1;i<=n;i++){
dp[i] = 1e9;
for (int j=0;j<i;j++){
dp[i] = min(dp[i], dp[j] + arev[j+1][i] + b[j][i]);
//cout<<i+1<<" "<<j<<" "<<arev[j+1][i]<<endl;
//cout<<i<<" "<<j<<" "<<b[j+1][i]<<endl;
}
}
cout<<dp[n]<<endl;
}
