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

Example Input: vFuggVITQuctFG, hdCIWWuuggVITQwr
Example Output: uggVITQ

Example Input: uHGHiARtdJbuG, OdZmiARtdrhC
Example Output: iARtd

Example Input: tnOYrsUTqoPOxyBtaNC, oDJUeDcbTqoPOxyBPyMcOMB
Example Output:
TqoPOxyB