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

[EX Q]: pySBCdpe, AEBCdOR
[EX A]: BCd

[EX Q]: JAfPtjqqUYMD, cpXItjqqFN
[EX A]: tjqq

[EX Q]: zKykjG, AmykRN
[EX A]:
yk

