What is the Pythonic way to find the longest common prefix of a list of lists?

Question

Given: a list of lists, such as [[3,2,1], [3,2,1,4,5], [3,2,1,8,9], [3,2,1,5,7,8,9]]

Todo: Find the longest common

Answer 1

It is inefficient as it doesn't early-out as soon as a mismatch is found, but its tidy:

([i for i,(j,k) in enumerate(zip(a,b)) if j!=k] or [0])[0]