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[] depths;
    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<>());
        }
        UnionFindTree uft = new UnionFindTree(n);
        int left = 0;
        int right = 0;
        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)) {
                left = a;
                right = 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];
        depths = new int[n];
        setDepth(0, 0, 0);
        while (left != right) {
            if (depths[left] == depths[right]) {
                ans.add(graph.get(left).get(parents[left]));
                left = parents[left];
                ans.add(graph.get(right).get(parents[right]));
                right = parents[right];
            } else if (depths[left] < depths[right]){
                ans.add(graph.get(right).get(parents[right]));
                right = parents[right];
            } else {
                ans.add(graph.get(left).get(parents[left]));
                left = parents[left];
            }
        }
        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) {
        depths[idx] = d;
        parents[idx] = p;
        for (int x : graph.get(idx).keySet()) {
            if (x != p) {
                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 (parents[x] == 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) {
            if (!same(x, 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();
    }
    
}