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

Q: HKCoXQsLRtowYJ, PGRzNUQsLRtoLcqkn

A: QsLRto
****
Q: vMsEJRoLkWcmkuwNRz, ZmoLkWcmVZiBv

A: oLkWcm
****
Q: uuQAtuUJaNMqJd, nPCLyFbJUQAtuUJaNMjjxn

A:
QAtuUJaNM
****