That's +2 actually!

lol, thumbs up on Butterfly Effect.

There seems to be a week point in the in-time-of-contest hacking. If someone with a fake ID (or lets say two friends) are in the same room, he may submit for N times (for an arbitrarily large amount of N) using his fake ID, and hack his solution with th original ID. This way, he gets 100*N points for free (which worths a lot for an arbitrarily large amount of N) :D
P.S. I can see that this way you will be mention his cheating and will disqualify him, but it's just a matter of canceling the potential of cheating as much as you can. Also, note that you won't even think of cheating if the process is done for a small value of N.

Solution: Don't let someone hack another ones solution for more than once (or twice)