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

[EX Q]: XpFCxFOgTTNCnQzMnVPV, FMqzdOwgTTNCnQzedorxVPe
[EX A]: gTTNCnQz

[EX Q]: mOGzbnDXWnNurkBXtcqZ, NLahGzbnDXWnNYgMTOR
[EX A]: GzbnDXWnN

[EX Q]: otFMHDBT, xkFMHMzz
[EX A]:
FMH