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

sUdaWtsiRgqAYHykrHwjyDvZgD, MJdFXYiRgqAYHykrakSGHMr
iRgqAYHykr

jXbgnl, lUbglP
bg

GCgZwc, OVgZTf

gZ