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

[EX Q]: AeYjeKwZQillzpD, SnqviKwZQillrxuTB
[EX A]: KwZQill

[EX Q]: QeNePjbLBKbDOuAVTJtXL, xjPVOyPbLBKbDOuDsMSEF
[EX A]: bLBKbDOu

[EX Q]: WiwSimGjmwweSETJsEH, SFqmGjmwwewRDC
[EX A]:
mGjmwwe