InfoPath Dev

Here is the requirement. Im using Infopath Designer 2010. There are five dropdown list boxes which has the same set of values in all the dropdown list boxes. Lets say the values are "A" and "B". And a display name "Select...." User can select only two B's and one A's. from those 5 boxes. If user selects more ...

 Im using Infopath Designer 2010. Here's the requirement. There are five dropdown list boxes in infopath form with same two values in each dropdown list box (lets say values are A and B) User cant select  the value "B" from these dropdown list boxes more than two times. If user selects B for third time, message ...