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

Q: YWNPkA, LuNPnN

A: NP
****
Q: DUhUbmfLuOFAQann, kwnzfLuOFAErR

A: fLuOFA
****
Q: kpThpk, lwThXR

A:
Th
****