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

[EX Q]: WjyKtxKtEYjP, vuBZJZyKtxKtXRZs
[EX A]: yKtxKt

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

[EX Q]: gOdZwG, JJdZlc
[EX A]:
dZ