How to find common elements in list of lists?

Question

I\'m trying to figure out how to compare an n number of lists to find the common elements. For example:

p=[ [1,2,3],
    [1,9,9],
      ..
      ..
    [1,2         


        

Answer 1

>>> p=[ [1,2,3],
    [1,9,9],
    [1,2,4]]
>>> set(p[0]).intersection(*p)
set([1])