case 1 failed
input:
7
1 6
4 6
1 5
3 5
1 3
1 7
2 6
expected:
NO
4 6 2 3 1 7 5
4 6 1 3 2 7 5
got:
NO
4 5 2 3 1 7 6
4 5 1 3 2 7 6