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

#define ll long long

bool add_node(set<ll>& xv, set<ll>& yv, pair<ll, ll> x) {
    bool r = true;
    if (xv.find(x.first) != xv.end() || yv.find(x.second) != yv.end())
        r = false;

    xv.insert(x.first);
    yv.insert(x.second);

    return r;
}

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

    multiset<pair<ll, ll>> e;
    for (int i = 0; i < n; i++) {
        ll a, b;
        cin >> a >> b;

        e.insert({a, b});
    }

    set<ll> xv, yv;
    int g_c = 0;
    for (pair<ll, ll> x : e) {
        if (add_node(xv, yv, x)) g_c++;
    }

    cout << g_c - 1 << '\n';
}

int main() {
    solve();
}