Answers

2016-06-20T21:26:27+08:00
{1,3,5,7,9}= {1},{3},{5},{7},{9}{1,3},{1,5},{1,7},{1,9},{3,5},{3,7},{3,9},{5,7},{5,9},{7,9},{1,3,5},{1,7,9}
1 2 1