#include <bits/stdc++.h>
#include <bits/extc++.h>
#define StarBurstStream ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define iter(a) a.begin(), a.end()
#define riter(a) a.rbegin(), a.rend()
#define lsort(a) sort(iter(a))
#define gsort(a) sort(riter(a))
#define pb(a) push_back(a)
#define eb(a) emplace_back(a)
#define pf(a) push_front(a)
#define ef(a) emplace_front(a)
#define pob pop_back()
#define pof pop_front()
#define mp(a, b) make_pair(a, b)
#define F first
#define S second
#define mt make_tuple
#define gt(t, i) get<i>(t)
#define tomax(a, b) ((a) = max((a), (b)))
#define tomin(a, b) ((a) = min((a), (b)))
#define topos(a) ((a) = (((a) % MOD + MOD) % MOD))
#define uni(a) a.resize(unique(iter(a)) - a.begin())
#define printv(a, b) {bool pvaspace=false; \
for(auto pva : a){ \
if(pvaspace) b << " "; pvaspace=true;\
b << pva;\
}\
b << "\n";}
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<ld, ld>;
using tiii = tuple<int, int, int>;
const ll MOD = 1000000007;
const ll MAX = 2147483647;
template<typename A, typename B>
ostream& operator<<(ostream& o, pair<A, B> p){
return o << '(' << p.F << ',' << p.S << ')';
}
ll ifloor(ll a, ll b){
if(b < 0) a *= -1, b *= -1;
if(a < 0) return (a - b + 1) / b;
else return a / b;
}
ll iceil(ll a, ll b){
if(b < 0) a *= -1, b *= -1;
if(a > 0) return (a + b - 1) / b;
else return a / b;
}
int n;
vector<int> p;
vector<bool> use;
vector<int> now;
int tmp = 0;
int ans;
void dfs(){
if((int)now.size() == n){
ans = min(ans, tmp);
//cerr << "test " << tmp << " " << ans << " ";
//printv(now, cerr);
return;
}
for(int i = 1; i <= n; i++){
if(use[i]) continue;
int mn = now.back();
int mx = now.back();
bool ok = true;
for(int j = (int)now.size() - 2; j >= 0; j--){
if(mx > now[j] && mx > i && mn < now[j] && mn < i){
ok = false;
break;
}
mx = max(mx, now[j]);
mn = min(mn, now[j]);
}
if(!ok) continue;
use[i] = true;
now.eb(i);
int sz = now.size();
if(p[sz] != i) tmp++;
dfs();
if(p[sz] != i) tmp--;
now.pob;
use[i] = false;
}
}
int main(){
StarBurstStream
cin >> n;
p.resize(n + 1);
use.resize(n + 1);
ans = n;
for(int i = 1; i <= n; i++) cin >> p[i];
for(int i = 1; i <= n; i++){
use[i] = true;
now.eb(i);
if(p[1] != i) tmp++;
dfs();
if(p[1] != i) tmp--;
now.pob;
use[i] = false;
}
cout << ans << "\n";
return 0;
}
