#pragma GCC optimize("O3")
#include <bits/stdc++.h>
using namespace std;
#define boost ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0)
#define rando mt19937 rng(chrono::steady_clock::now().time_since_epoch().count())
#define fi first
#define se second
#define debug(x) cerr << " - " << #x << ": " << x << endl;
#define debugs(x, y) cerr << " - " << #x << ": " << x << " " << #y << ": " << y << endl;
#define debugii(x) cerr << " - " << #x << ": " << x.fi<<","<<x.se << endl;
#define sep() cerr << "--------------------" << endl;
#define all(x) (x).begin(),(x).end()
#define sz(x) (ll)x.size()
#define ld long double
#define ll long long
#define int ll
#define ii pair<int,int>
#define v vector<int>
#define vii vector<ii>
#define vv vector<vector<int> >
#define mp make_pair
#define INF 1e14
#define pb push_back
#define EPS 1e-9
const int MOD = 1000000007; // 998244353
int xs[2002],ys[2002];
int32_t main(){
	boost;
	//freopen(".in","r",stdin);
	int n;
	cin>>n;
	v vec;
	for (int i = 0; i < n; ++i){
		cin>>xs[i]>>ys[i];
		vec.pb(i);
	}
	int ans=0;
	while(!vec.empty()){
		ans++;
		int max_x=-INF,max_y=-INF,min_x=INF,min_y=INF;
		for(auto it:vec){
			max_x=max(max_x,xs[it]);
			max_y=max(max_y,ys[it]);
			min_x=min(min_x,xs[it]);
			min_y=min(min_y,ys[it]);
		}
		v n_vec;
		for(auto it:vec){
			if((xs[it]==min_x||xs[it]==max_x)&&(ys[it]<=max_y)&&(ys[it]>=min_y))continue;
			if((ys[it]==min_y||ys[it]==max_y)&&(xs[it]<=max_x)&&(xs[it]>=min_x))continue;
			n_vec.pb(it);
		}
		vec=n_vec;
	}
	cout<<ans;
	return 0;
}
//long long
//array bounds
//special cases
//binary search