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

Example Input: TdvkBvVyJcSdYGGPfnyml, rIvIvVyJcSdYhtxG
Example Output: vVyJcSdY

Example Input: XpFCxFOgTTNCnQzMnVPV, FMqzdOwgTTNCnQzedorxVPe
Example Output: gTTNCnQz

Example Input: kAhGSOWHWBVwrm, HeOWHWBVwTthHXFf
Example Output:
OWHWBVw