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]: IJQqdzqdaGEIcdyh, izlVdzqdaGGiPYz
[EX A]: dzqdaG

[EX Q]: mScpMKRhVaxcgS, BHBwtKRhVaxctLLsi
[EX A]:
KRhVaxc