# booklets with at most 0 intersections:

       0        0  a01 b01 c01
       1        7  a02 b02 c02

# booklets with at most 1 intersections:

# booklets with at most 2 intersections:

       2        1  a02 b01 c01
       3        6  a01 b02 c02

       4        2  a01 b02 c01
       5        5  a02 b01 c02

       6        3  a02 b02 c01
       7        4  a01 b01 c02

