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

[EX Q]: lLxXqKscqizXTO, TqrKscqizutDudo
[EX A]: Kscqiz

[EX Q]: aBlALASwuwTZmy, MdwASwuwIW
[EX A]: ASwuw

[EX Q]: YkXRceY, jrXRcGH
[EX A]:
XRc