A to B

You are given two points $A = (x_1, y_1, z_1)$ and $B = (x_2, y_2, z_2)$ in the 3D coordinate system. You would like to start at point $A$ and reach point $B$. To do this, you can move in any of the $6$ cardinal directions — up, down, left, right, front or back — one step at a time. Formally, in one step, you can choose exactly one coordinate and either increase or decrease it by $1$. Howev