How to add a condition during the cumulated calculation?

Dear KNIME community,

I been struggling to find out a way how to add conditions if in the cumulations

as this table below that i have the workflow to run the cumulation by sub category → column “Sum(Qty)”

But I need the condition to verify if the result of the cumul >0, then will be as 0 in the next level cumulation → as column “Condition Cumul Qty”

Thank you for your guidance, appreciated it!

KR,

Chrystal