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

cKsJcqYvZO, UrsJcqBC
sJcq

IVnbnqBqdPcXfHotUzCYoaGQy, PAlyypBRRBqdPcXfHotpZs
BqdPcXfHot

xNQTstWGKoqtVBRFdVBrMYvQ, jZeWGKoqtVBRFsGQvzzt

WGKoqtVBRF