// Wounds should become scars but I'm cracked instead U+1FAE0
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
#define all(x) (x).begin(),(x).end()
#define X first
#define Y second
#define sep ' '
#define endl '\n'
#define debug(x) cerr << #x << ": " << x << endl;
const ll MAXN = 1e6 + 10;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int n, T[MAXN], P[MAXN], F[MAXN], ind[MAXN];
bool P_val[MAXN];
inline int rand_perm() {
int l = 1, r = n;
int fl = 1, fr = n;
int ans = n;
fill(P_val, P_val + n + 5, false);
for (int i = 1; i <= n; i++) {
if (P[l] == fl) {
ans--;
l++;
fl++;
P_val[fl] = true;
} else if (P[l] == fr) {
ans--;
l++;
fr--;
P_val[fr] = true;
} else if (P[r] == fl) {
ans--;
r--;
fl++;
P_val[fl] = true;
} else if (P[r] == fr) {
ans--;
r--;
fr--;
P_val[fr] = true;
} else {
// if (P_val[fl]) fl++;
// else if (P_val[fr]) fr--;
if (rng() % 2) fl++;
else fr--;
if (P[l] < fl || P[l] > fr) P_val[P[l]] = true, l++;
else if (P[r] < fl || P[r] > fr) P_val[P[r]] = true, r--;
else if (rng() % 2)
P_val[P[l]] = true, l++;
else
P_val[P[r]] = true, r--;
}
}
return ans;
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin >> n;
for (int i = 1; i <= n; i++) cin >> P[i];
int fuck = 10000000 * 13 / n;
int ans = n;
while (fuck--) {
ans = min(ans, rand_perm());
}
cout << ans << endl;
return 0;
}
