instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
cUCQXEFSgRZjK, RYdvUQXEFSgRZVlwx
answer:
QXEFSgRZ


question:
jJjsASFfCqVV, AkjsASFfBFwPy
answer:
jsASFf


question:
EpXdioTyELmJztBj, mOTywxudioTyELmfsnum
answer:

dioTyELm