#include<iostream>
#include<vector>
#include<map>
using namespace std;
struct arc {
    vector<int> y;
    vector<int> x;
};
#define FF(x, y, z) for(int x =y; x < z; x++)

int main() {
    vector<arc> vec;
    int n;
    cin >> n;
    map<int, bool> rows;
    map<int, bool> cols;
    int max_id =0;

    FF(i, 0, n) {
        int x, y;
        cin >> x >> y;
        int row_id = rows[x];
        int cols_id = cols[y];

        if (row_id && cols_id) {
            max_id--;
        }
        else if (row_id || cols_id){}
        else {
            max_id++;
        }
        rows[x] = true;
        cols[y] = true;
    }
    cout << max_id -1 << endl;
    return 0;
}