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

void testcase() {
    ll n, components = 0;
    cin >> n;

    set<ll> rows, cols;
    for(ll i = 0; i < n; ++i) {
        ll x, y;
        cin >> x >> y;
        auto rows_res = rows.insert(x);
        auto cols_res = cols.insert(y);
        if(rows_res.second && cols_res.second) components++;
    }
    cout << components - 1 << "\n";
}



int main() {
    testcase();
}