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

Example Input: Owbiay, exbime
Example Output: bi

Example Input: yITbYie, TlqTbYomH
Example Output: TbY

Example Input: OCYnfMMOKiIawxPcED, wdyvnfMMOKiIUINwhGUw
Example Output:
nfMMOKiI