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

[EX Q]: yrIDSuVuQU, UXTSuVuLcch
[EX A]: SuVu

[EX Q]: TdvkBvVyJcSdYGGPfnyml, rIvIvVyJcSdYhtxG
[EX A]: vVyJcSdY

[EX Q]: yFKNSfhkKuQYVoYI, aKktNSfhkKuQYoP
[EX A]:
NSfhkKuQY