Ubuntu 20.04. libmraa0.4 How to manage a button with ISR

Hello, I’m new to libmraa (this is the 0.4 version, can’t have v2 work apparently)

When I try to use the gpio_advanced.cpp example, it fails because the pin nimber is always incorrect.

I managed to use sysfs, to write to a pin called 860 on my system (exporting it, settig direction and writing 1 to value)

But I need to use some non shellscript language, C, C++ or python, to handle a button press.

Can’t find any pin number…
I’m stuck atm.