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

Q: nYoRQU, gQoRZQ

A: oR
****
Q: SIIPePlrkftKkzfgdjg, JqNnXHrkftKkzOMUwmc

A: rkftKkz
****
Q: fNwqWfPXXkDDQNYh, UnDmWfPXXkDBgj

A:
WfPXXkD
****