int bfs(vector<list<int>>& graph, int member) {
    vector<bool> visited(N + 1, false);
    queue<int> q;
    q.push(member);
    visited[member] = true;

    int distance = 0;
    while (!q.empty()) {
        int size = q.size();
        for (int i = 0; i < size; i++) {
            int cur = q.front();
            q.pop();
            for (int curFriend : graph[cur]) {
                if (!visited[curFriend]) {
                    q.push(curFriend);
                    visited[curFriend] = true;
                }
            }
        }
        distance++;
    }

    if (isConnected(visited)) return distance;
    return -1;
}

#include <iostream>
#include <list>
#include <queue>
#include <vector>
#include <algorithm>
#include <climits>

using namespace std;

int N;

void printResult(vector<pair<int, int>>& result) {
    cout << result[0].first << " " << result.size() << '\n';
    for (auto& p : result) cout << p.second << " ";
}

int bfs(vector<list<int>>& graph, int member) {
    vector<bool> visited(N + 1, false);
    vector<int> distances(N + 1, 0);
    queue<int> q;
    q.push(member);
    visited[member] = true;

    while (!q.empty()) {
        int cur = q.front();
        q.pop();

        for (int curFriend : graph[cur]) {
            if (!visited[curFriend]) {
                q.push(curFriend);
                visited[curFriend] = true;
                distances[curFriend] = distances[cur] + 1;
            }
        }
    }

    if (find(visited.begin() + 1, visited.end(), false) != visited.end()) return -1;
    return *max_element(distances.begin(), distances.end());
}

int main() {
    cin >> N;

    vector<list<int>> graph(N + 1);
    while (true) {
        int a, b;
        cin >> a >> b;
        if (a == -1 && b == -1) break;

        graph[a].push_back(b);
        graph[b].push_back(a);
    }

    vector<pair<int, int>> result;
    int minDistance = INT_MAX;
    for (int i = 1; i <= N; i++) {
        int distance = bfs(graph, i);
        if (distance == -1) continue;
        if (distance < minDistance) {
            result.clear();
            minDistance = distance;
        }
        if (distance == minDistance) result.emplace_back(minDistance, i);
    }

    if (!result.empty()) printResult(result);

    return 0;
}