input:

10000
2 1
1 2
29 28
13 19
16 5
21 7
22 10
10 2
1 18
27 13
10 3
11 23
12 22
11 7
7 17
29 17
9 1
28 21
2 18
13 9
4 25
20 16
5 14
20 7
14 4
12 8
8 24
17 19
15 1
11 6
26 9
13 12
13 9
12 2
6 12
9 11
5 2
8 10
6 10
3 10
7 1
7 5
8 9
4 1
12 11
10 6
2 8
12 4
5 10
11 1
3 1
10 1
12 9
9 1
8 3
7 1
35 35
13 8
34 1...

output:

2 
7 10 11 14 15 16 17 18 22 24 25 26 27 28 
3 4 5 8 9 12 
1 2 3 4 9 10 
3 5 9 13 15 18 23 24 26 28 29 30 31 32 33 34 35 
4 8 10 11 12 13 15 16 18 
2 
3 4 
7 10 13 15 17 21 22 24 26 27 28 31 33 35 37 39 40 42 43 44 46 47 48 49 50 
1 4 5 7 11 12 13 18 21 22 23 26 28 29 33 34 35 36 
1 3 4 5 10 13 14 
...

result:

wrong answer vertex 19 is not covered (test case 20)