It's definitely more than three.
We have the following that I'm aware of:
(1) in the IT closet; (1) in the electronics lab; (1) in the East room, (1) in the West room, and (1) in the vault hallway.
Electronics lab is a gifted/eval AP from Cisco (Meraki MR18); its license expires 7/10/2017;
IT Closet, East Room, and West room are various units from Tony.
Vault hallway is a Cisco WAP4410N.
I'd love for MMS to grab a handful (6ish should be plenty) of Ubiquiti gear. The units I'd recommend are Unifi AP AC Pro's, and run about $100 a pop.
-Chris