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

Q: mQvintdwLUpClREgxv, rYnoXBtdwLUpClRwxsqX

A: tdwLUpClR
****
Q: wYhGWdRC, cFGWdHEy

A: GWd
****
Q: ZvEjOXzjJQlkpr, JvlXzjJQYVKu

A:
XzjJQ
****