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 
class BerlandRoads():
    def __init__(self, n, edges):
        self.n = n
        self.edges = edges
        self.parents = [i for i in range(n)]
        self.sizes = [1 for i in range(n)]

    def find(self, v):
        while self.parents[v] != v:
            temp = self.parents[v]
            self.parents[v] = self.parents[temp]
            v = temp
        return v

    def union(self, u, v):
        u = self.find(u)
        v = self.find(v)
        if u == v:
            return False
        else:
            if self.sizes[u] > self.sizes[v]:
                self.parents[v] = u
                self.sizes[u] += self.sizes[v]
            else:
                self.parents[u] = v
                self.sizes[v] += self.sizes[u]
            return True

    def build_roads(self):
        rem_edges = []
        for u,v in self.edges:
            if not self.union(u-1,v-1):
                rem_edges.append((u,v))
        tree_reps = []
        for i in range(n):
            if self.parents[i] == i:
                tree_reps.append(i)
        for i in range(len(rem_edges)):
            vals = [rem_edges[i][0],rem_edges[i][1],tree_reps[i], tree_reps[i+1]]
            print(*vals)

n = int(input())
edges = []
for i in range(n-1):
    u,v = list(map(int,input().strip(' ').split(' ')))
    edges.append((u,v))

br = BerlandRoads(n, edges)
br.build_roads()
                