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

[EX Q]: RJMYumLAlhmnbhzKRzIOWsGrxGu, VEViqlihmnbhzKRzIBArjAhYrz
[EX A]: hmnbhzKRzI

[EX Q]: SIIPePlrkftKkzfgdjg, JqNnXHrkftKkzOMUwmc
[EX A]: rkftKkz

[EX Q]: wZWvCmbdAinGqzjfemmACur, qQrExdAinGqzjfelWyW
[EX A]:
dAinGqzjfe