In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.

Q: XqyPjqNZDEK, EfwPjqNgjIP

A: PjqN
****
Q: SIIPePlrkftKkzfgdjg, JqNnXHrkftKkzOMUwmc

A: rkftKkz
****
Q: FYiUAbtknhMKdOzh, zCAbtknhFrAhBC

A:
Abtknh
****