Divisible by 3

Stack likes the number $3$ a lot. He has two non-negative integers $A$ and $B$. In one operation, Stack can do either of the following: - $A:=|A-B|$ (change $A$ to $|A-B|$) - $B:=|A-B|$ (change $B$ to $|A-B|$) Note that $|X|$ denotes absolute value of $X$. For example $|-7| = 7$ and $|4| = 4$. Find the **minimum** number of operations after which **at least** one integer out of $A$ and $B$