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

[EX Q]: jXbgnl, lUbglP
[EX A]: bg

[EX Q]: OhMVLbQhBxEaOZY, iDVLbQhBxBiiD
[EX A]: VLbQhBx

[EX Q]: SQNzngllNbOkKDK, MijfNzngllNDfWge
[EX A]:
NzngllN