#include<iostream>
#include<string>
#include<iomanip>
#include<cmath>
#include<vector>
#include<algorithm>
#include<utility>
#include<deque>
#include<map>

using namespace std;

#define int long long
#define endl "\n"

constexpr long long INF = (long long)1e18;
constexpr long long MOD = 1'000'000'007; 

struct fast_io {
	fast_io(){
		std::cin.tie(nullptr);
		std::ios::sync_with_stdio(false);
	};
} fio;


bool cycle_detection(const vector<vector<int>> &G, vector<bool> &used, vector<bool> &used2, deque<int> &C, int cur, int per){
	used[cur] = true;
	used2[cur] = true;
	
	C.push_back(cur);
    
	for(int nex : G[cur]){
		if(used[nex]){
			if(used2[nex]) { 
                if(per == nex) continue;
                
				while(C.front() != nex){
					C.pop_front();
				}
				return true;
			} else {
				continue;
			}
		}
		
		if(cycle_detection(G, used, used2, C, nex, cur)) return true;
	}
	
	C.pop_back();
	
	used2[cur] = false;
	
	return false;
}

deque<int> cycle_detection(const vector<vector<int>> &G){
	int N = G.size();
	vector<bool> used(N), used2(N);
	deque<int> C;
	
	for(int i = 0; i < N; i++){
		if(used[i] == true) continue;
		C.clear();
		if(cycle_detection(G, used, used2, C, i, -1)) return C;
	}
	
	return {};
}

signed main(){
	cout<<fixed<<setprecision(10);
	
	int N;
    vector<vector<int>> G;
    deque<int> c;
    map<pair<int,int>, int> mp;
    
    cin>>N;
	
    G.resize(N);
    
	for(int i = 0; i < N; i++){
        int a, b;
        
        cin>>a>>b;
        
        a--, b--;
        
        G[a].push_back(b);
        G[b].push_back(a);
        
        mp[{a,b}] = i + 1;
        mp[{b,a}] = i + 1;
    }
    
    c = cycle_detection(G);
    
    cout<<(int)c.size();
    
    for(int i = 0; i < c.size(); i++){
        cout<<" "<<mp[{c[i], c[(i+1)%c.size()]}];
    }
    cout<<endl;
    
    // for(int i = 0; i< c.size(); i++){
        // cout<<" "<<c[i];
    // }
    // cout<<endl;
	return 0;
}