#include <stdio.h>
#include <iostream>
#include <stdlib.h>
#include <string>
#include <string.h>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <assert.h>
#include <algorithm>
#include <iomanip>
#include <time.h>
#include <math.h>
#include <bitset>
#include <fstream>

#define int uint64_t

using namespace std;

int32_t main() {
    ios_base::sync_with_stdio(false);
    set<pair<int,int>> data;
    vector<pair<int,int>> data2;
    int n,xa,ya;
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> xa >> ya;
        data.emplace(xa,ya);
        data2.emplace_back(xa,ya);
    }
    int counter = 0;
    for (int i = 0; i < n; i++) {
        auto x = data.upper_bound({data2[i].first, 0});
        auto y = data.upper_bound({data2[i].second, 0});
        bool flag = true;
        while (x != data.end()) {
            if (x->second > data2[i].second){
                flag = false;
                break;
            }
            x++;
        }
        while (y != data.end() && flag) {
            if (y->second > data2[i].first){
                flag = false;
                break;
            }
            y++;
        }
        counter += flag;
    }
    cout << counter;
}