instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
LJJvLTK, jpFJvLqh
answer:
JvL


question:
JAGuNgaUudP, eojvKNgaUuQg
answer:
NgaUu


question:
GVVEaubFlJ, OzMEaubjfO
answer:

Eaub