#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

const int N = 1e5 + 7;
int n, c[N], r[N], root, ans, siz[N], mini[N], maxi[N];

vector <int> e[N];

void DFS (int u) {
	siz[u] = 1, mini[u] = u, maxi[u] = u;
	for (int it = 0; it < e[u].size(); ++it) {
		int v = e[u][it];
		DFS (v);
		mini[u] = min (mini[u], mini[v]);
		maxi[u] = max (maxi[u], maxi[v]);
		siz[u] += siz[v];
	}
}

int main () {
	scanf ("%d", &n);
	for (int i = 1; i < n; ++i) {
		int u, v;
		scanf ("%d%d", &u, &v);
		e[u].push_back(v);
		c[u]++, r[v]++;
	}
	for (int i = 1; i <= n; ++i) 
		if (r[i] == 0) root = i;
	DFS (root);
	int ans = 0;
	for (int i = 1; i <= n; ++i) 
		if (maxi[i] - mini[i] + 1 == siz[i]) ++ans;
	cout << ans << endl;
	return 0;
}