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

[EX Q]: UTdardKNThdYrGKMqZPeg, mvrThdYrGKMlcCxBtak
[EX A]: ThdYrGKM

[EX Q]: yJRITYgVTSNsPjG, NSIdKYgVTSNmj
[EX A]: YgVTSN

[EX Q]: kmdMuBkKXfdKbPe, whOBkKXfMPCFU
[EX A]:
BkKXf