instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
AkYuNemHGBEDF, uluNemHGAycbWX
answer:
uNemHG


question:
ftvxfhsnJEygzV, JYxSfhsnJnIqkW
answer:
fhsnJ


question:
RyaNyUvXAaZHLXUtYuz, CkbsWxZyUvXAaZHLXJJzugDy
answer:

yUvXAaZHLX