#include <bits/stdc++.h>
using namespace std;
int countInversions(vector<int>& arr) {
int inv_count=0;
int n=arr.size();
for (int i=0; i<n; i++){for (int j=i+1; j<n; j++) {if (arr[i]>arr[j]){inv_count++;}}}return inv_count;}
int solve_perm(vector <int> v){
vector <pair<int,int>> tm;
for (int i=0; i<v.size(); i++){tm.push_back({v[i],i});}
int mn=INT_MAX;
sort(tm.begin(),tm.end());
do {
int ans=1;
for (int i=1; i<tm.size(); i++){if (tm[i].first+2<=tm[i-1].first){ans=0;}}
if (ans==1){
vector<int> permutation;
for (auto& p : tm){
permutation.push_back(p.second);}
int swaps = countInversions(permutation);
mn = min(mn, swaps);
}
} while (next_permutation(tm.begin(), tm.end()));
return mn;
}
int solve_binary(vector <int> v){
int n=v.size();
int total=1<<(n);
vector <int> pos(n+1);
for (int i=0; i<n; i++){pos[v[i]]=i;}
int mn=INT_MAX;
for (int mask=0; mask<total; mask++){
vector<int> groups;
for (int i=0; i<n; i++){
if (mask&(1<<i)){
groups.push_back(i+1);
}
}
vector <pair<int,int>> tm;
if (groups.size()!=0){
int j=0;
int lst=0;
int lt=0;
for (int i=0; i<n; i++){
if (lst-1<i){
if (j!=groups.size()){
tm.push_back({groups[j],pos[groups[j]]});
lst=groups[j];
lt=lst;
j++;}
else{break;}
}
else{
lt--;
tm.push_back({lt,pos[lt]});
}
}
vector<int> permutation;
if (tm.size()==n){
for (auto& p : tm){permutation.push_back(p.second);}
int swaps=countInversions(permutation);
mn=min(mn,swaps);}
/*for (int i=0; i<tm.size(); i++){cout<<tm[i].first<<' ';}
cout<<"\n";
*/
groups.clear();
}}
return mn;
}
int main(){
int n;
cin>>n;
vector <int> v(n);
for (int i=0; i<n; i++){
cin>>v[i];
}
//cout<<solve_perm(v)<<"\n";
cout<<solve_binary(v);
}
