#include <algorithm>
#include <bits/stdc++.h>
using namespace std;

int main() {
	int n, cnt = 0;
    cin >> n;
    vector<pair<int, int>> v(n);
    map<int, int> napok;
    for(int i = 0; i < n; i++) cin >> v[i].first >> v[i].second;
    sort(v.begin(), v.end());
    for(int i = 0; i < n; i++) {
        if(napok.count(v[i].first)) napok[v[i].first]--;
        if(napok.count(v[i].second)) napok[v[i].second]++;
        else napok.insert({v[i].second, 1});
        //for(int j = 0; j < n; j++) if(napok.count(v[i].second)) cout << v[i].second << ":" << napok[v[i].second] << " ";
        //cout << endl;
    }
    set<int> volt;
    for(int i = 0; i < n; i++) if(!volt.count(v[i].second)) {
        //cout << v[i].second << " " << napok[v[i].second] << endl;
        cnt += napok[v[i].second];
        volt.insert(v[i].second);
    }
    cout << cnt << endl;
}