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

[EX Q]: KKrCLvJKRoyV, WDeLvJKCBdS
[EX A]: LvJK

[EX Q]: wkVVZREWhcSCpvCTB, ZQWhcSCpvCDVUY
[EX A]: WhcSCpvC

[EX Q]: oZHNiElxsoCYGXl, cSuusfmElxsoCYGSl
[EX A]:
ElxsoCYG