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

[EX Q]: nXVXIEGP, fkXIEkU
[EX A]: XIE

[EX Q]: SUgXyznbUQRpiLUTlRb, jlnwLTnbUQRpioUFyJ
[EX A]: nbUQRpi

[EX Q]: JAfPtjqqUYMD, cpXItjqqFN
[EX A]:
tjqq