#include <bits/stdc++.h>

using Pos = std::pair<long long int, long long int>;
int main ()
{
    size_t N;
    std::cin >> N;
    long long int x, y;
    std::vector<Pos> positions, same_y;
    size_t cnt = 0;
    for (size_t i = 0; i < N; ++i)
    {
        std::cin >> x >> y;
        positions.push_back({x,y});
        same_y.push_back({y,x});
    }
    std::sort(positions.begin(), positions.end(), [&] (const Pos & a, const Pos & b){
        if (a.first == b.first) return a.second < b.second;
        return a.first < b.first; 
    });
    std::sort(same_y.begin(), same_y.end(), [&] (const Pos & a, const Pos & b){
        if (a.first == b.first) return a.second < b.second;
        return a.first < b.first; 
    });

    std::vector<std::pair<Pos, int>> res, res_y;
    for (const auto & i : positions)
    {
        res.push_back({i, -1});
    }

    res[0].second = 0;
    for (size_t i = 1; i <= N; ++i){
        if(res[i-1].first.first == res[i].first.first){
            res[i].second = res[i-1].second;
        }
        else{
            res[i].second = res[i-1].second + 1;
        }
    }
    for (size_t i = 1; i <= N; ++i){
        if(res[i-1].second != res[i].second && res[i].first.second == res[i-1].first.second){
            res[i].second = res[i-1].second;
        }
    }
    std::set<int> a;
    for (size_t i = 0; i < res.size(); ++i){
        a.insert(res[i].second);
    }
    

    std::cout << a.size() - 1 << std::endl;
    return 0;
}