In problem 220B - Little Elephant and Array my submission 36377029 got WA. Then I comment ios_base::sync_with_stdio(0) and submit the same code 36377330 again. It got accepted. Now I wonder why my first code got WA and when we should use ios_base::sync_with_stdio(0) and when we shouldn't.

In problem 937C - Save Energy!, my accepted code's 36137732 output differs from jury's answer on test case 27. But cf compiler gives ok verdict. Then I checked some other AC code. All AC code gives the same output as mine in that case. So what's the actual problem?

There is no option to delete your comment on any cf post. Generally there's no problem because it forces you to think before commenting and prevent any immature comment. But problem occurs when someone edit there blog totally and now your comment not only seems to weird but also stupid on that blog. Though you can edit your comment but sometimes you find nothing relevant to say on that new topic.

So I want to say that if writer of a blog edits his/her blog then there should be an option to delete comment for all who comment before editing that blog.