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

[EX Q]: ftvxfhsnJEygzV, JYxSfhsnJnIqkW
[EX A]: fhsnJ

[EX Q]: QEEVsnbQIgrxaZmflaZ, dPSbljkdQIgrxaZmgVzMT
[EX A]: QIgrxaZm

[EX Q]: AiYNreqMpv, ZEUNreqFO
[EX A]:
Nreq