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

[EX Q]: OXdSmcKG, XbDdSmJl
[EX A]: dSm

[EX Q]: eeoJEtGHPDvHck, ezPGHPDvHSf
[EX A]: GHPDvH

[EX Q]: hKaYuTOjcOmdVCk, dLuTOjcOmXB
[EX A]:
uTOjcOm