instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
rvLoiycpZw, idcvoiycpcLyD
answer:
oiycp


question:
HqaOvLaZbs, RifOvLaZkh
answer:
OvLaZ


question:
VbEbAv, UkEbeN
answer:

Eb