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

Example Input: YKpdeJQhzyYiPoODACUu, mjmnIlCehzyYiPoOzZ
Example Output: hzyYiPoO

Example Input: dReySjyqecU, loSjyqiRl
Example Output: Sjyq

Example Input: vHrllOYRwMMxzdQTeF, APxHJGElOYRwMMZq
Example Output:
lOYRwMM