instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
OUNqomxFcLXhWdfB, gdqomxFcLHQPCu
answer:
qomxFcL


question:
QvtDqzQiSknPbRCG, hVxHdqzQiSknPbumdpNIf
answer:
qzQiSknPb


question:
jvkuCLJFjqKH, YDuCLJFjGd
answer:

uCLJFj