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

[EX Q]: OUNqomxFcLXhWdfB, gdqomxFcLHQPCu
[EX A]: qomxFcL

[EX Q]: xMxyohPBlJIEBqghiMdBQPwq, xsBlJIEBqghlMosK
[EX A]: BlJIEBqgh

[EX Q]: KBGDqO, XUGDYZ
[EX A]:
GD