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

[EX Q]: ljwjMioOwfOltGBaE, TneNGsoOwfOlxnWWW
[EX A]: oOwfOl

[EX Q]: oWwqraAz, uxTqraonu
[EX A]: qra

[EX Q]: RnXdQXYSMUDztutEBBuz, qltNXYSMUDztjCWUqhkz
[EX A]:
XYSMUDzt