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

[EX Q]: VTwtMVKmrRvL, WLoVtWtMVKmrDCke
[EX A]: tMVKmr

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

[EX Q]: pIkAtJHVcvzzZVz, btWerNSHVcvzzZTz
[EX A]:
HVcvzzZ