I was participating in meta hacker cup as practice round is going on now. But for 2/3 questions for which the submissions i made i got presentation error. And at this point i am not able to figure out much what were the difference between them. So can someone tell me how to handle this so i don't mess up because of this.(As the contest is still going on i am not sure if i should share my code here but if someone wants i can share it to him/her personally).

Edit: One thing which i forgot to mention i solved some problems from last year as well and all those question which had single line output like "Case #1: 5" these tend to work fine but only those which had multiple lines output seem to fail(Not sure if that's the correct reasoning or not).