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

[EX Q]: eJPZzg, lFPZbI
[EX A]: PZ

[EX Q]: plSfJAktMfac, TCjYJAktlt
[EX A]: JAkt

[EX Q]: hCOiDmZQeKU, OKUiDmZJrA
[EX A]:
iDmZ