Posts from Monster recruitment trigger. Auto-translated

Hello, I'm slowly learning about ERM instructions, receivers, and triggers while creating a simple map. And now, I need to limit the number of units a hero can hire. For example, he can't hire dragons (maximum number - 0), but he can hire angels, but only up to 5. Something like that.
But I've run into a problem: I can't find a unit hiring trigger where I can catch everything I need. So, I decided to ask the Gurus for help with my question; I think this question will be of interest to more than just me.
Thank you in advance.