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

[EX Q]: KTAFonizDqCVvucpJWrItdw, rfFonizDqCVvYbGhb
[EX A]: FonizDqCVv

[EX Q]: WFAPUCgVYbmZiFlacUzyv, xQFiekrgPUCgVYbmZUEtl
[EX A]: PUCgVYbmZ

[EX Q]: JzbEpAquDJFKcNvEWZxVqRV, PFiJlpAquDJFKcNcqOpMeAv
[EX A]:
pAquDJFKcN