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

[EX Q]: YWNPkA, LuNPnN
[EX A]: NP

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

[EX Q]: txJhzNeBj, qLJhzNesV
[EX A]:
JhzNe