instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
kyADtWLlnmYv, tcaKvDtWLlnvBq
answer:
DtWLln


question:
sHndIbPaygfNvnquxIHeteW, huLmJWXZIgfNvnquxIViQDhbuoL
answer:
gfNvnquxI


question:
FCedAQnAYtuPb, qObuaAQnAYsFck
answer:

AQnAY