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

[EX Q]: jFVaEHbMrrkW, ekfVaEHbPnBnM
[EX A]: VaEHb

[EX Q]: PivhPfah, XSghPfOi
[EX A]: hPf

[EX Q]: ujNxxLztBPgm, PJvoLztBPoeAce
[EX A]:
LztBP