In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
--------
Question: VRXUhOYfTul, JqZUhOYKq

Answer: UhOY


Question: CxwZWv, mkwZgM

Answer: wZ


Question: DOQdIiwNnrvKqoZJ, XQIiwNnrvKqzOzSiJdId

Answer:
IiwNnrvKq