[L4D1/2] Check if entity is inside map transition trigger?
 

I want to manage the numbers of first aid kits available according to the survivor count every time a map starts.

I've decided the best way to do it is to count the number of first aid kits inside the transition trigger once the map transition starts, check if it's too low, then create the rest of the missing medkits on a position of one of the available medkits, or, if not available, a player.

But how do I check whether the medkits are able to transition to the next map?