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

[EX Q]: UldKHMpUYADGfEUGcSon, nPHMpUYADGfEKqHCLPmL
[EX A]: HMpUYADGfE

[EX Q]: nxoXDohHr, WcbkXDohFbJ
[EX A]: XDoh

[EX Q]: mXDWrFkSGvEpG, FnIWrFkSTizn
[EX A]:
WrFkS