As we all know, hacks are a useful part of Codeforces which are different from many other online judges. But why can't I try to hack solutions of anyone else after a contest not a long time? In fact, I cannot find a button like "Hack it!". Is it because I'm a newbie without joining in enough contests? Can anyone please explain the reasons to me? Thanks!

UPD: Thanks for the comments! The answer to this question can be found here.