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

[EX Q]: VXSNlHzkB, EoNlHCiL
[EX A]: NlH

[EX Q]: KKebLWQCQzVIojj, nxQCQzVIopD
[EX A]: QCQzVIo

[EX Q]: XsNkiRpnMVELi, BkIkiRpnMkg
[EX A]:
kiRpnM