instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
xfZYYDKEqoRRu, ztCeYYDKEqoPG
answer:
YYDKEqo


question:
mmDhYqPJC, qThYqxW
answer:
hYq


question:
SwiAdI, oViAEz
answer:

iA