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

[EX Q]: mmDhYqPJC, qThYqxW
[EX A]: hYq

[EX Q]: YCAyruPTTHWhCYaiXfIl, OETdzqAyruPTTHWgS
[EX A]: AyruPTTHW

[EX Q]: IKNvGU, VnNvXA
[EX A]:
Nv