Boolean extrusion issue

Good evening fellow users,

This time i have a question concerning the boolean statement. Fex, I have 2 curves, and I always want grasshopper to check which line is higher(has greater z) and extrude it upwards( + z direction), and the one with lower z, extrude it downwards( - z direction).

Picture extr1

Small curve has greater z so it extrudes upwards ( + z direction) and long curve extrudes downwards( - z direction)

Picture extr2

Long curve has greater z so it extrudes upwards ( + z direction) and small curve extrudes downwards( - z direction)

I want to make a script that recognise which curve is higher on z and extrude them accordingly.