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

[Q]: PQSFjlnU, kTSFjMUh
[A]: SFj


[Q]: xtCJGe, DXCJSw
[A]: CJ


[Q]: aXDEDFijeVXHrVIN, YPzUEdyFijeVXHrVTL
[A]:
FijeVXHrV