제출 #122902

5 4
3 2
1 3
1 4
3 5

1 3 1 4 3

1 3 4 2 5 

student 1 appears more than once

4 6
1 4
1 2
2 4
3 4
3 1
3 2

1 3 2 1

3 1 2 4 

student 1 appears more than once

7 10
2 3
6 3
7 3
2 5
1 5
4 3
1 3
7 5
4 5
6 5

2 6 7 4 1 7 4

1 2 4 6 7 3 5 

student 7 appears more than once