#include <iostream>
#include <string.h>
#include <algorithm>
#include <cmath>
#include <set>
#include <iomanip>
#include <limits.h>
#include <functional>
#include <string>
#include <vector>
#include <tuple>
#include <stack>

using namespace std;

const int INF = (int) 1e7;

int cycle_st = -1, cycle_end = -1;

void dfs(vector<vector<int>> &g, vector<int> &color, int v, stack<int> &move) {
	color[v] = 1;
	move.push(v);
	for (int i : g[v]) {
		if (color[i] == 1 && i != v) {
			cycle_end = v;
			cycle_st = i;
		}
		if (color[i] == 0) {
			dfs(g, color, i, move);
		}
	}
	color[v] = 2;
}

int main() {
	int n;
	cin >> n;
	vector<vector<int>> g(n);

	for (int i = 0; i < n; ++i) {
		int a, b;
		cin >> a >> b;
		--a; --b;
		g[a].push_back(b);
		g[a].push_back(a);
	}
	vector<int> color(n);
	stack<int> move;
	dfs(g, color, 0, move);
	bool x = false;
	vector<int> cycle;

	while (!move.empty()) {
		if (move.top() == cycle_end)
			x = true;

		if (move.top() == cycle_st)
			x = false;

		if (x) {
			cycle.push_back(move.top() + 1);
		}
		move.pop();
	}
	cycle.push_back(cycle_st + 1);
	reverse(begin(cycle), end(cycle));
	cout << cycle.size() << endl;

	for (int i : cycle)
		cout << i << " ";

#ifdef DIMA_DEBUG
	system("pause");
#endif // DIMA_DEBUG

}