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

HXYkGv, GCYksu
Yk

wDSKHtWbCDqTeoBeiYHdcZD, MydQCwqTeoBeiYHdYMp
qTeoBeiYHd

jDzGalVdGxR, HQQStalVdGmLvjq

alVdG