instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
YcgVJVACcQE, JsJVACcSz
answer:
JVACc


question:
QvtDqzQiSknPbRCG, hVxHdqzQiSknPbumdpNIf
answer:
qzQiSknPb


question:
uCYkPYyqUjyb, vZwdvPYyqUPg
answer:

PYyqU