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

[EX Q]: SQNzngllNbOkKDK, MijfNzngllNDfWge
[EX A]: NzngllN

[EX Q]: mjCEUoPmeKbvCgUtUL, SrHtrPmeKbvYpQAVp
[EX A]: PmeKbv

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