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

[EX Q]: vhZuXCsIkQR, YflCuXCsIkLu
[EX A]: uXCsIk

[EX Q]: DwLGzwYOWjtzIunE, TTViSbkwYOWjtzNqUOOz
[EX A]: wYOWjtz

[EX Q]: hjykdMZtIJAMPe, TjyNJFdMZtIJMIM
[EX A]:
dMZtIJ