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

[EX Q]: lypuwWy, jRpuwcE
[EX A]: puw

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

[EX Q]: qXNsIZly, tbrNsIDwY
[EX A]:
NsI