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

vJtmxQmHEq, yobgAtmxQmMeoLz
tmxQm

TnbLNKnNSs, NhDLNKnNRd
LNKnN

hXlGiVrIogIsupHtDgzMHa, NdKPgCSIogIsupHtmTyViJIJ

IogIsupHt