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

vJtmxQmHEq, yobgAtmxQmMeoLz
tmxQm

VLxrvK, gvxrac
xr

JLjWsnVbzLaFirbHvjnTz, YXMvzavVlSnVbzLaFirbVCssFqKzH

nVbzLaFirb