How to get highest value from 4 different columns for each person

Summary:

I am trying to retrieve the highest value from 4 fields for each person

For example these four people have various values in the 4 columns (some are null)

The results I need are just showing the highest value for the 4 columns

Also, I need to exclude any columns that may be blank.

I am using the "Workforce Profiles - Person Profile Real Time" Subject Area to get this calculation but also I am using

"Workforce Management - Worker Assignment Real Time" and "Workforce Management - Person Real Time"

Is there a way of producing this information?

My current xml is attached.