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

Q: AxRSlkQfWHrdlgQG, iXIOrmlkQfWHTy

A: lkQfWH
****
Q: ftvxfhsnJEygzV, JYxSfhsnJnIqkW

A: fhsnJ
****
Q: GPWWbotCa, BNVWbogO

A:
Wbo
****