Active Directory User Office Location problem

Hello All,

My app’s first page has a combo box that contains a list of office locations (cboOfficeLocations – Teksys-CA, Teksys-NJ, Teksys-NY etc.) and a Lable lblUserOfficeLocation.text
After the user connected to the app, he/she has to select his/her current office location so that he/she can be allowed to access the right data. It’s currently working fine for users that belong to single office location, but it’s not for users that belong to multiple office locations.

When a user who belongs to two office locations logs into the app, the lblUserOfficeLocation.text shows his/her office locations as Teksys-NJ/Teksys-NY; (I pulled this out from AD), I have to determine what his/her first office location name is and then set it as the default location in the combo box cboOfficeLocation. In this case, the cboOfficeLocation has to show Teksys-NJ as the default office location. 
My problem is that I don't know how to figure out the first office location name.
Would someone please help me out with this? 

Your help is greatly appreciated!
Thank you very much in advance!