Screen Tap with multiple actions

I’m developing an filter with 3 Rigid objects.
When the user tap on screen, one falls. Than the user tap again and the second 3d object fall. Then user tap again and the 3th object fall.
I did a node with an ~if~condition, but works only with 2 objects…

Where can I learn more about the script to solve that issue and another that will come in the future?