//無向グラフでの各種dfs
//計算量 パス検出:O(E+V)、閉路検出:O(E+V)

//verified with
//https://yukicoder.me/problems/no/1254

#include <bits/stdc++.h>
using namespace std;

struct io_setup{
    io_setup(){
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        cout << fixed << setprecision(15);
    }
} io_setup;

struct Graph{
    vector<vector<int>> es;
    vector<int> used;
    vector<int> keep;
    const int n;

    Graph(int n) : n(n){
        es.resize(n), used.resize(n);
    }

    void add_edge(int from, int to, bool directed = false){
        es[from].emplace_back(to);
        if(!directed) es[to].emplace_back(from);
    }

    bool trace(int now, int t){
        used[now] = true;
        if(now == t) {keep.emplace_back(now); return true;}
        for(auto &e : es[now]){
            if(used[e]) continue;
            if(trace(e, t)) {keep.emplace_back(now); return true;}
        }
        return false;
    }

    vector<int> find_path(int s, int t){
        keep.clear(), fill(begin(used), end(used), 0);
        trace(s, t), reverse(begin(keep), end(keep));
        return keep;
    }

    int detect(int now, int pre){
        if(used[now]++) return 1;
        for(auto &e: es[now]){
            if(e == pre) continue;
            int k = detect(e, now);
            if(k == 2) return 2;
            if(k == 1) {keep.emplace_back(now); return used[now];}
        }
        return 0;
    }

    vector<int> find_loop(){
        keep.clear(), fill(begin(used), end(used), 0);
        for(int i = 0; i < n; i++){
            if(used[i]) continue;
            detect(i, -1);
            if(!keep.empty()) {reverse(begin(keep), end(keep)); return keep;}
        }
        return keep;
    }
};

int main(){
    int V; cin >> V;

    Graph G(V);
    map<pair<int, int>, int> mp;

    for(int i = 0; i < V; i++){
        int u, v; cin >> u >> v; u--, v--;
        G.add_edge(u, v);
        mp[minmax(u, v)] = i;
    }
    
    vector<int> loop = G.find_loop();
    int n = loop.size();
    cout << n << '\n';

    for(int i = 0; i < n; i++){
        int j = (i+1)%n;
        cout << mp[minmax(loop[i], loop[j])]+1 << ' ';
    }
    cout << '\n';
}