#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair <int, int> pii;
#define pb push_back
#define all(a) a.begin(), a.end()
#define sz(a) ((int)a.size())
const int mod = 998244353, N = 100001;

typedef pair<int, int> pi;
vector<int> g[N];
int dep[N], pa[N];
map<int, pi> mp;
int rt[N], cnt[N];
int find(int i) {
	return rt[i] < 0 ? i : (rt[i] = find(rt[i]));
}
void onion(int i, int j) {
	i = find(i), j = find(j);
	if (i != j)
		rt[i] += rt[j], rt[j] = i;
}
bool vis[N];
void dfs(int i, int p) {
	vis[i] = true;
	pa[i] = p, dep[i] = ~p ? dep[p] + 1 : 0;
	for (int j : g[i])
		if (!vis[j])
			dfs(j, i);
}
int main() {
	ios::sync_with_stdio(false), cin.tie(0);
	int n;
	cin >> n;
	fill(rt, rt + n, -1);
	for (int i = 0; i < 2 * n - 3; ++i) {
		int x, y;
		cin >> x >> y;
		--x, --y;
		g[x].push_back(y), g[y].push_back(x);
		onion(x, y);
	}
	for (int i = 0; i < n; ++i)
		cnt[find(i)] += g[i].size();
	for (int i = 0; i < n; ++i)
		if (rt[i] <= -3 && cnt[i] / 2 >= 2 * (-rt[i]) - 3) {
			dfs(i, -1);
			for (int x = 0; x < n; ++x)
				if (vis[x]) {
					for (int y : g[x])
						if (dep[y] < dep[x] && y != pa[x]) {
							if (mp.count(dep[x] - dep[y])) {
								cout << dep[x] - dep[y] + 1 << '\n';
								int l = mp[dep[x] - dep[y]].first, r = mp[dep[x] - dep[y]].second;
								while (l != r)
									cout << l + 1 << ' ', l = pa[l];
								cout << r + 1 << '\n';
								l = x, r = y;
								while (l != r)
									cout << l + 1 << ' ', l = pa[l];
								cout << r + 1 << '\n';
								return 0;
							}
							mp[dep[x] - dep[y]] = pi(x, y);
						}
				}
			int sz = -rt[i];
			cout << "3\n" << mp[sz - 1].first + 1 << ' ' << mp[sz - 1].second + 1 << ' ';
			if (mp[sz - 2].first == mp[sz - 1].first || mp[sz - 2].first == mp[sz - 1].second)
				cout << mp[sz - 2].second + 1 << '\n';
			else
				cout << mp[sz - 2].first + 1 << '\n';
			int l = mp[2].first, r = mp[2].second;
			while (l != r)
				cout << l + 1 << ' ', l = pa[l];
			cout << r + 1 << '\n';
			return 0;
		}
}