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

Q: vytthSjj, XVttthSFAvk

A: tthS
****
Q: rduIwWNGM, AJqYIwWNaCap

A: IwWN
****
Q: QmzCwkyuudyygzVhXFK, pwHiiWMkudyygzVhXPFpxNZ

A:
udyygzVhX
****