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

[EX Q]: zeuyZKwvIOfx, BlmZKwvspUt
[EX A]: ZKwv

[EX Q]: YPeBvuJXaSLLPhKpUQ, ryjPdyuJXaSLLPhIzBeJP
[EX A]: uJXaSLLPh

[EX Q]: MYSExy, kLSEUr
[EX A]:
SE