instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
QvtDqzQiSknPbRCG, hVxHdqzQiSknPbumdpNIf
answer:
qzQiSknPb


question:
yITbYie, TlqTbYomH
answer:
TbY


question:
LJUoOLXexmC, hsUoOLXpgp
answer:

UoOLX