#include <bits/stdc++.h>

using namespace std;
using ll = long long;
int main()
{
    std::ios::sync_with_stdio(false);

    ll N;
    cin >> N;
    unordered_set<ll> x;
    unordered_set<ll> y;
    ll count = 0;
    ll x_0, y_0;
    cin >> x_0 >> y_0;
    x.insert(x_0);
    y.insert(y_0);
    for (int i = 1; i < N; i++)
    {
        ll x_0, y_0;
        cin >> x_0 >> y_0;
        if (x.find(x_0) == x.end() && y.find(y_0) == y.end())
        {
            count++;
        }
        x.insert(x_0);
        y.insert(y_0);
    }
    cout << count << endl;
}