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

[Q]: jeQzwP, kSQzxq
[A]: Qz


[Q]: JzbEpAquDJFKcNvEWZxVqRV, PFiJlpAquDJFKcNcqOpMeAv
[A]: pAquDJFKcN


[Q]: IFnnsfCwgsC, YVHHsfCwgJTL
[A]:
sfCwg