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

[EX Q]: OFbCjZDoRRlLsMU, DcCjZDoRRtld
[EX A]: CjZDoRR

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

[EX Q]: wLaMEgNsDtDfctDIOp, SexXmCqNsDtDfcXGNGy
[EX A]:
NsDtDfc