#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(min(xa,ya), max(xa,ya));
        data2.emplace_back(min(xa,ya), max(xa,ya));
    }
    int counter = 0;
    for (auto obj : data2) {
        bool is_found = false;
        for (auto el : data) {
            if (el.first > obj.first && el.second > obj.second) {
                is_found = true;
                break;
            }
        }
        if (!is_found)
            counter++;
    }
    cout << counter;
}