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

[EX Q]: OXdSmcKG, XbDdSmJl
[EX A]: dSm

[EX Q]: CkZOSZevST, bbZOSZIg
[EX A]: ZOSZ

[EX Q]: MzqDCp, ylqDah
[EX A]:
qD