How to calculate E-Pz variable of two final state particles in madanalysis

p e- > j e-
I generate the above process using MadGraph and analyse the LHE file using Madanalysis.
I want to calculate the E-Pz variable of the final state electron and jet in Madanalysis.
Finally I want to reject events with E-Pz less than some value.
Do I need to go to the expert mode to calculate this in Madanlysis?
It would be helpful if you kindly let me know about this.