2000, 1, 2
2, 4, 6, 8, 10, 12, 14, 16, 18
4, 6, 8, 10, 12, 14, 16, 18
6, 8, 10, 12, 14
14, 16, 18
1, 2, 4, 6
6, 8, 10, 12, 14, 16
1, 2
1, 2, 4, 6, 8, 10, 12, 14, 16, 18