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

[EX Q]: OVZxWYzAAxG, rStOxWYzJeoC
[EX A]: xWYz

[EX Q]: XEvxzelZaWRO, zXIelZaWBUn
[EX A]: elZaW

[EX Q]: SuCIGUhb, fFCIGWKc
[EX A]:
CIG