#include <bits/stdc++.h>
using namespace std;
vector<vector<int>> isReverse;
int getReverse(int l,int r){
int ret = 0;
// for(int i = l;i <= r;i++){
// for(int j = i;j <= r;j++){
// ret += isReverse[i][j];
// }
// }
ret = isReverse[r][r]-isReverse[l-1][r]-isReverse[r][l-1]+isReverse[l-1][l-1];
return ret;
}
int main(){
cin.tie(0);
ios_base::sync_with_stdio(0);
//start here
int N;
cin >> N;
vector<int> v(N+1);
vector<int> loc(N+1);
for(int i = 1;i <= N;i++){
cin >> v[i];
loc[v[i]] = i;
}
isReverse = vector<vector<int>>(N+1,vector<int>(N+1,0));
int total = 0;
for(int i = 1;i <= N;i++){
for(int j = i+1;j <= N;j++){
if(loc[i] > loc[j]){
isReverse[i][j] = -1;
total++;
}else{
isReverse[i][j] = 1;
}
}
}
// makes it prefix;
for(int i = 1;i <= N;i++){
for(int j = 1;j <= N;j++){
isReverse[i][j] += isReverse[i-1][j]+isReverse[i][j-1]-isReverse[i-1][j-1];
}
}
vector<int> dp(N+1,0);
dp[0] = 0;
for(int i = 1;i <= N;i++){
// chose a range to reverse
for(int j = i;j >= 1;j--){
int cost = getReverse(j,i);
// cout << j << " "
dp[i] = min(dp[i],dp[j-1]+cost);
}
}
// for(int i = 1;i <= N;i++)cout << loc[i] << " ";cout << endl;
// for(int i = 1;i <= N;i++)cout << dp[i] << " ";cout << endl;
// cout << total << endl;
cout << total+dp[N];
}
