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

FCKbAgSVgj, wAEAWbAgSVSVwD
bAgSV

yKtQOhYvrJVH, HQsTQOhYvPP
QOhYv

tlYUjxcZCZFycchKDN, MSZCZFycchrLAFiM

ZCZFycch