#include <bits/stdc++.h>
using namespace std;

template <class T>
ostream& operator<<(ostream& out, const vector<T> &cont) {
    out << "[";
    for(const auto &x: cont) out << x<< ", ";
    out << "]";
    return out;
}

#define dmp(x) cerr << #x << " = " << x << endl
#define dmpn(x) cerr << #x << " = " << x <<"; "

#define ff first
#define ss second
#define all(x) begin(x), end(x)
#define sz(x) (int) (x).size()
#define int long long

typedef long long ll;
typedef pair<int, int> pii;
typedef long double ld;


void solve() {
    int n;
    cin >> n;

    set<int> lines, rows;
    int components = 0;

    for(int i=0; i<n; i++){
        int x, y;
        cin >> x >> y;

        if(lines.find(x) == lines.end() && rows.find(y) == rows.end())
            components++;

        lines.insert(x);
        rows.insert(y);
    }

    cout << components-1 << '\n';

}

int32_t main() {
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);
    solve();
    return 0;
}