instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
hRVyvwHqnN, geHeyvwHqiBiYJ
answer:
yvwHq


question:
mQvintdwLUpClREgxv, rYnoXBtdwLUpClRwxsqX
answer:
tdwLUpClR


question:
iXXxZMHnju, AKXxZMyqsP
answer:

XxZM