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]: lLxXqKscqizXTO, TqrKscqizutDudo
[EX A]: Kscqiz

[EX Q]: NhLuDyXXXLjHzwEIszQkpmMTF, TpRXLjHzwEIsAVK
[EX A]:
XLjHzwEIs