It's impossible to tell.
WHen I tried to figure it out, it just went in a circle.
Assume A is telling the truth then B is lying so then C tells truth so then A is lying and it throws off about B lying.
Assume B is telling the truth then A and B would be truth, and if A and B would be true then with A being true that means B would be lying.
Assume C would be telling the truth, that means A is a liar, so what ever a says about B is a lie so then B must be telling the truth, and if B tells the truth that means C is a liar so whatever C says about A and B is a lie so then A and B are telling the truth. And if A and B are telling the truth then according to A. B is lying and so B says C is a liar but according to A he is lying so then C must be telling the truth, it just goes in oooooone big circle!