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

[EX Q]: ktABEFESAVHZkkY, uMjxiESAVHZkZgWUte
[EX A]: ESAVHZk

[EX Q]: PivhPfah, XSghPfOi
[EX A]: hPf

[EX Q]: eygpuT, yZgpEM
[EX A]:
gp