case 1 failed: expected "YES\n7\n1 8\n8 3\n3 6\n6 5\n5 2\n2 7\n7 1" got "YES\n5\n7 1\n2 1\n7 2\n1 8\n1 3"
input:
1
8 18
2 7
5 6
1 7
2 5
2 6
1 8
6 7
3 6
1 2
4 7
4 8
3 8
6 8
7 8
4 5
3 4
2 3
1 3