In my first contest, how many problems do I have to get right in order to go straight to expert level? Or should I just solve one problem and from then get my ranking high. Also, how do I get my ranking high? Do I have to solve a lot of problems in a contest, or do some hacking? For contribution, I just wanted to know what the meaning of it is. Does it affect anything? I only just started this website so I'm not really sure... :)