In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.

Example Input: KKebLWQCQzVIojj, nxQCQzVIopD
Example Output: QCQzVIo

Example Input: BdqUloJanutXoOyfLsuA, NRDloJanutXoOQY
Example Output: loJanutXoO

Example Input: ZKiQgzHOyYziXePahXHLUNb, sfUzHOyYziXeWD
Example Output:
zHOyYziXe