instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
nuwMzarLqoPvabJla, JKcrLqoPvabJNDCILGQ
answer:
rLqoPvabJ


question:
vytthSjj, XVttthSFAvk
answer:
tthS


question:
qiPeFUibYob, ThxkFUibkE
answer:

FUib