Comb of (number) character ...

I am a beginner in Adobe LiveCycle application, and I apologize for any confusion, but if someone can help, how to make a dynamic form, with the following elements (the IBAN account):

     1. Drop down list with name of state (Albania, Andora, ...)

     2. text field with : 2 character of state (ex. Albania = 'AL',  Andora = 'AN', ...)  + variable number characters of each state comb of (number) character (ex. Albania 28, Andora 24, ...)

So, can something like:

          {

               this.numericField3.ui.numericEdit.comb.numberOfCells = "28"

          }    

elseif (DropDownList2 == "Andora")

          {

               this.numericField3.ui.numericEdit.comb.numberOfCells = "24"

          }

.....

endif;