Triangular arbitrage

Simple question on Triangular arbitrage:

If I have currencies A,B,C.

How do I know I have to set the triangle as, suppose: A-B-C-A and not A-C-B-A? Because it gives a loss/profit, so I might get the question wrong if the question asks “is there a profit of X or loss of Y”

Do you get my point?

Cheers!