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

int main() {
	int N;
	cin >> N;
	vector<pair<long long, long long>> a(N);
	for(int i = 0; i < N - 1; i++){
		cin >> a[i].first >> a[i].second;
	}

	//sort(a.begin(), a.end());
	for(int i = N-1; i >= 0; i--){
		for(int j = i-1; j >= 0; j--){
			if(a[j].second == a[i].first){
				a[j].second = a[i].second;
				a.erase(a.begin() + i);
				break;
			} 
		}
	}

	cout << a.size();
}