List Possible Combinations With Conditions/Constraints

I am trying to write VBA code that will list all possible combinations of data contained in a worksheet based on a few conditions. I have a list that varies in length. In the first column is a list of numbers denoting a particular course number. In the second column is a list of numbers denoting the specific class number for the course. As an example, I have a 6 courses. The first course has 1 class, the second course has 3 classes, the third has 11, the fourth has 3, the fifth has 7, and the sixth has 6. Thus, my columns look like this:

A B
1 1
2 1
2 2
2 3
3 1
3 2
3 3
3 4
3 5
...

I need to list out all possible combinations of classes given that I must have all six courses. EXAMPLE (Course, Class):.......................