Need to know plug tip polarity

I have an Axis A23 that I’d like to either keep using or give to a friend’s kid. Only problem is, I’ve lost the wall adapter it came with, and the the tablet itself doesn’t specify whether it requires a positive center or negative center plug tip. All it (unhelpfully) says is, “DC-5V”. I’m looking to buy a universal, reversible polarity wall adapter for it, but I know if I plug it in backwards, I could potentially fry the thing. So, if anyone still has theirs along with its wall adapter, could you please let me know what the plug tip polarity is?