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

[EX Q]: gTjTwC, OUjTgM
[EX A]: jT

[EX Q]: PivhPfah, XSghPfOi
[EX A]: hPf

[EX Q]: ZzGuTnYxtK, MdcEGuTnUILB
[EX A]:
GuTn