#include <bits/stdc++.h>
using namespace std;
const int MAX = 1e5+5;

map<string, int> to;
string a, b;

vector<int> order, gr[MAX];
int n, used[MAX], comp[MAX];
int cnt_comp[MAX], cmp, ans;

void dfs(int u) {
	used[u] = true;
	for (int to : gr[u]) {
		if (!used[to]) {
			dfs(to);
		}
	}
	order.push_back(u);
}

void dfs2(int u, int cmp) {
	used[u] = 2;
	comp[u] = cmp;
	++cnt_comp[comp[u]];
	if (cnt_comp[comp[u]] == 2) ++ans;
	for (int to : gr[u]) if (used[to] != 2) {
		dfs2(to, cmp);
	}
}

int main() {
	ios_base::sync_with_stdio(0), cin.tie(0);
	while (cin >> a >> b) {
		if (!to.count(a)) {
			to[a] = n++;
		}
		if (!to.count(b)) {
			to[b] = n++;
		}
		int s = to[a], t = to[b];
		gr[s].push_back(t);
	}
	for (int i = 0; i < n; ++i) {
		if (!used[i]) dfs(i);
	}
	for (int i = 0; i < n; ++i) {
		int u = order[i];
		if (used[u] != 2) {
			dfs2(u, cmp);
			++cmp;
		}
	}
	cout << ans << '\n';
}