import java.io.*;
import java.util.*;
import java.util.stream.*;

public class Main {
    static ArrayList<HashMap<Integer, Integer>> graph = new ArrayList<>();
    static int[] parents;
    static int[] depth;
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        for (int i = 0; i < n; i++) {
            graph.add(new HashMap<>());
        }
        int p = 0;
        int q = 0;
        UnionFindTree uft = new UnionFindTree(n);
        ArrayList<Integer> ans = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            int a = sc.nextInt() - 1;
            int b = sc.nextInt() - 1;
            if (uft.same(a, b)) {
                p = a;
                q = b;
                ans.add(i);
            } else {
                uft.unite(a, b);
                graph.get(a).put(b, i);
                graph.get(b).put(a, i);
            }
        }
        parents = new int[n];
        depth = new int[n];
        setDepth(0, 0, 0);
        while (depth[p] != depth[q]) {
            if (depth[p] < depth[q]) {
                ans.add(graph.get(q).get(parents[q]));
                q = parents[q];
            } else {
                ans.add(graph.get(p).get(parents[p]));
                p = parents[p];
            }
        }
        while (p != q) {
            ans.add(graph.get(p).get(parents[p]));
            p = parents[p];
            ans.add(graph.get(q).get(parents[q]));
            q = parents[q];
        }
        StringBuilder sb = new StringBuilder();
        sb.append(ans.size()).append("\n");
        for (int i = 0; i < ans.size(); i++) {
            if (i > 0) {
                sb.append(" ");
            }
            sb.append(ans.get(i) + 1);
        }
        System.out.println(sb);
    }
    
    static void setDepth(int idx, int p, int d) {
        parents[idx] = p;
        depth[idx] = d;
        for (int x : graph.get(idx).keySet()) {
            if (p != x) {
                setDepth(x, idx, d + 1);
            }
        }
    }
    
    static class UnionFindTree {
        int[] parents;
        
        public UnionFindTree(int size) {
            parents = new int[size];
            for (int i = 0; i < size; i++) {
                parents[i] = i;
            }
        }
        
        public int find(int x) {
            if (x == parents[x]) {
                return x;
            } else {
                return parents[x] = find(parents[x]);
            }
        }
        
        public boolean same(int x, int y) {
            return find(x) == find(y);
        }
        
        public void unite(int x, int y) {
            parents[find(x)] = find(y);
        }
    }
}
class Utilities {
    static String arrayToLineString(Object[] arr) {
        return Arrays.stream(arr).map(x -> x.toString()).collect(Collectors.joining("\n"));
    }
    
    static String arrayToLineString(int[] arr) {
        return String.join("\n", Arrays.stream(arr).mapToObj(String::valueOf).toArray(String[]::new));
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public int[] nextIntArray() throws Exception {
        return Stream.of(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}