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

[EX Q]: vJtmxQmHEq, yobgAtmxQmMeoLz
[EX A]: tmxQm

[EX Q]: BUvWkxrAvDQG, rHrkxrAkCE
[EX A]: kxrA

[EX Q]: LKYYidbGYZJgM, elidbGYZrGgU
[EX A]:
idbGYZ