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

[EX Q]: PQCjJwXurLeN, vsjJwXuOy
[EX A]: jJwXu

[EX Q]: skZGHS, HsZGge
[EX A]: ZG

[EX Q]: rvNArJBzjoVCV, iphcqArJBzjWtdxc
[EX A]:
ArJBzj