Add row number in matrix

Hi everyone,

I have a matrix that looks like this:

How do I add row numbers to the matrix? The matrix can be expanded multiple levels. I've tried some solutions I found on the internet and I couldn't figure out how to make it work and most of the solutions I found are used with tables instead of matrix. 

Additional note: 

- I'm using Direct Query

- Matrix can be sorted by either Sales or Qty

Any help is appreciated! Thank you