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

[EX Q]: PivhPfah, XSghPfOi
[EX A]: hPf

[EX Q]: ahPbomjSH, rBbomynK
[EX A]: bom

[EX Q]: JcEhiVznyEBACO, NaMSRiVznyEBaE
[EX A]:
iVznyEB