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

HSsyZzZLZAAq, MFEZzZLJC
ZzZL

yQCDWefwvrPP, RwoMDWefwhSxTR
DWefw

vZRNFOOcyML, uDnRNFOOmPq

RNFOO