instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
VXSNlHzkB, EoNlHCiL
answer:
NlH


question:
sOSXbnluNuvwMETKda, JzXbnluNuvyeVHO
answer:
XbnluNuv


question:
kECRwwNlcCIYltzc, DFbeKcRMtwNlcCIYlttcWWeW
answer:

wNlcCIYlt