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

[Q]: trHTzJpm, aCHTzVVA
[A]: HTz


[Q]: TnHJcxtwcZ, XFdHJcxNKw
[A]: HJcx


[Q]: xsMsMQGTgs, MCqMsMQEj
[A]:
MsMQ