#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef vector<ll> vl;
typedef vector<int> vi;
typedef vector<pii> vii;
typedef vector<pll> vll;
#define st first
#define nd second
#define FOR(i,j,k) for(auto i = (j); i<(k); i++)
#define ROF(i,j,k) for(auto i = (k)-1; i>=(j); i--)
#define sz(x) ((int)x.size())
#define all(x) x.begin(),x.end()
#define pb push_back
#define BOOST ios_base::sync_with_stdio(0);cin.tie(0);
const int MN = 21;
const int MM = 2e5+10;
const ll inf = 1e18+2;
vi V;
void gen(int mask, int n)
{
bitset<MN> M = mask;
int i = 0;
while(i<n)
{
int j = i;
while(M[j]) j++;
V.pb(j);
ROF(k,i,j) V.pb(k);
i = j+1;
}
}
int c(int n, vi C)//koszt uzyskania V z C
{
int rep = 0;
FOR(i,0,n)
{
int k = V[i];
int p = i;
while(C[p] != k) p++;
while(p>i)
{
swap(C[p],C[p-1]);
p--;
rep++;
}
}
return rep;
}
int main()
{
int n;
cin>>n;
vi C(n);
FOR(i,0,n)
{
cin>>C[i];
C[i]--;
}
int ans = 1e9+7;
FOR(m,0,1<<(n-1))
{
V.clear();
gen(m,n);
ans = min(c(n,C),ans);
}
cout<<ans;
}
