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

jkGcUm, dxGcSI
Gc

TdvkBvVyJcSdYGGPfnyml, rIvIvVyJcSdYhtxG
vVyJcSdY

xsoomaQGEsuRRRQL, wesyWaQGEsuATpGu

aQGEsu