#include <iostream>

#include <vector>

#include <queue>

#define p pair<int, int>

using namespace std;

vector< vector<int> > graph;

vector<int> dfn, low;

priority_queue<p, vector<p>, greater<p>> result;

int dep;

void dfs(int cur, int par)

{

	dfn[cur] = low[cur] = ++dep;

	for (auto& i : graph[cur]) {

		if (!dfn[i]) {

			dfs(i, cur);

			low[cur] = min(low[cur], low[i]);

		}

		else if (i != par) low[cur] = min(low[cur], dfn[i]);

		p tmp = { min(i, cur), max(i, cur) };

		if (low[i] > dfn[cur]) result.emplace(tmp);

	}

}

int main()

{

	int N;

	while (cin >> N) {

		graph.assign(N, vector<int>());

		dfn.assign(N, 0);

		low.assign(N, 0);

		dep = 0;

		for (int i = 0, a, b, n; i < N; ++i) {

			char tmp;

			cin >> a >> tmp >> n >> tmp;

			while (n--) cin >> b, graph[a].emplace_back(b);

		}

		for (int i = 0; i < N; ++i) if (!dfn[i]) dfs(i, -1);

		cout << result.size() << " critical links\n";

		while (!result.empty()) {

			cout << result.top().first << " - " << result.top().second << "\n";

			result.pop();

		}

		cout << "\n";

	}

	return 0;

}