so im looking to buy a power adapter because i forgot mine where i was on Holiday. I wont be getting it back until next friday. In the mean time i have no way to charge the damn thing. I've seen a couple of listings on craigslist but they have different ones, 40w, 60 and so on... I really don't know which one would be compatible with my 2011 13inch core i5 MBP. Should i get some guidance on this issue from the great members of this board, i'd be extremely thankful.