4
1 4
3 1
3 4
 5
4 1
4 3
5 3
2 4
 21
7 15
13 1
14 3
4 10
2 3
16 18
17 20
16 20
8 4
3 12
2 17
13 11
16 1
13 2
13 5
8 9
6 14
3 17
16 9
13 8
 3
3 1
3 2
 6
5 2
5 3
1 4
3 1
5 6
 60
17 34
46 22
50 44
46 33
41 21
31 33
48 6
38 19
35 60
2 24
49 29
7 53
34 1
19 55
32 1
31 42
27 28
4 53
6 50
21 34
1 10
12 36
54 8
16 13
51 43
45 51
54 20
13 53
34 33
49 33
51 11
59 34
15 5
59 28
30 39
13 30
58 4
34 14
3 9
19 34
4 18
26 48
56 54
3 43
57 25
3 41
35 3
48 44
19 13
54 1
23 31
59 47
5 1
46 40
6 26
20 25
37 5
17 24
20 52
 3
3 2
1 2
 39
6 13
15 39
10 35
31 28
4 21
12 39
3 7
3 13
6 1
5 14
36 28
12 15
18 38
30 29
19 34
36 16
20 22
8 13
38 32
26 39
21 37
1 7
15 27
12 26
8 3
6 14
29 2
25 23
32 21
5 16
32 25
6 8
13 10
23 30
34 37
29 33
28 14
36 5
 10
5 9
8 5
7 6
7 9
3 9
2 1
7 2
3 6
7 1

1
3 4 1 2  0
 3
13 2 1 7 3 17 1 19 13 8 1 21  0
 0
 2
48 44 1 6 6 26 1 12  0
 7
12 15 1 2 1 7 1 9 12 26 1 11 8 3 1 12 6 8 1 17 28 14 1 20 36 5 1 24  2
3 6 1 4 7 1 1 10 
import java.util.ArrayList;
import java.util.Scanner;


public class D {

    static ArrayList<Integer>[]ages;
    static int[]color;
    static int c = 0, n;
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        n = sc.nextInt();
        ages = new ArrayList[n+1];
        for (int i = 1; i <= n; i++) {
            ages[i] = new ArrayList<Integer>();
        }
        for (int i = 1; i < n; i++) {
            int v1 = sc.nextInt();
            int v2 = sc.nextInt();
            ages[v1].add(v2);
            ages[v2].add(v1);
        }
        color = new int[n+1];
        for (int i = 1; i <= n; i++) {
            if (color[i]==0) {
                c++;
                dfs(i, 0);
            }
        }
        System.out.println(0);
    }
    private static void dfs(int v, int p) {
        color[v] = c;
        for (int to : ages[v]) {
            if (to==p)
                continue;
            if (color[to]==0)
                dfs(to, v);
            else {
                System.out.println(1);
                System.out.print(v+" "+to+" ");
                int k1 = 0, k2 = 0;
            A:  for (int i = 1; i <= n; i++) {
                    if (color[i] == c) {
                        k1 = i;
                        for (int j = 1; j <= n; j++) {
                            if (color[j] != c) {
                                k2 = j;
                                break A;
                            }
                        }
                    }
                }
                System.out.println(k1+" "+k2);
                System.exit(0);
            }
        }
    }

}
