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

[EX Q]: BfCCzPNLBbwCoxMVAG, vhwNLBbwCbH
[EX A]: NLBbwC

[EX Q]: ylyLVUjsmMrXMFAPDGIZsHq, cYymMrXMFAPjm
[EX A]: mMrXMFAP

[EX Q]: DDfFHWQErlbTQKCHdr, CAiVmQQErlbTQDlVSt
[EX A]:
QErlbTQ