#include<iostream>
#include<vector>
#include<algorithm>
#include<cstring>
#include<cassert>
#include<cmath>
#include<ctime>
#include<iomanip>
#include<numeric>
#include<stack>
#include<queue>
#include<map>
#include<unordered_map>
#include<set>
#include<unordered_set>
#include<bitset>
#include<random>
#include<functional>
#include<utility>
using namespace std;
int N,s,seen[1 << 17],finished[1 << 17];
vector<int> G[1 << 17],path;
void dfs(int u,int p)
{
	seen[u] = 1;
	path.push_back(u);
	for(int v:G[u]) if(!finished[v] && v != p)
	{
		if(seen[v]) s = v;
		else dfs(v,u);
		if(s >= 0) return;
	}
	finished[u] = 1;
	path.pop_back();
}
void solve()
{
	cin >> N;
	map<pair<int,int>,int> E;
	for(int i = 0;i < N;i++)
	{
		int u,v;
		cin >> u >> v;
		u--; v--;
		G[u].push_back(v);
		G[v].push_back(u);
		E[minmax(u,v)] = i;
	}
	s = -1;
	dfs(0,-1);
	vector<int> cycle;
	while(true)
	{
		int u = path.back();
		cycle.push_back(u);
		if(u == s) break;
		path.pop_back();
	}
	cout << cycle.size() << endl;
	for(int i = 0;i < (int)cycle.size();i++) cout << E[minmax(cycle[i],cycle[(i+1)%(int)cycle.size()])]+1 << (i+1 == (int)cycle.size() ? "\n":" ");
}
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int tt = 1;
	//cin >> tt;
	while(tt--) solve();
}