I live in an apartment with a garden shared by 2 houses, there's usually 2 or 3 cats spending their days here while my neighbors are at work.
Recently a cat was in the entrance (a common entrance, with a direct access on the garden) and asked for petting every time I came back to work.
Yesterday night (at 10 PM) I came home and he was there, I petted him a bit then went to my apartment but he followed me all the way and tried to enter in my apartment. I didn't let him in but he meowed behind the door for 5 minutes, and started again 1 hour later.
How should I make him understand he can't come in my apartment ?