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

Example Input: dReySjyqecU, loSjyqiRl
Example Output: Sjyq

Example Input: YHLJZrFQ, aSLJZQuo
Example Output: LJZ

Example Input: UGqbQEBYyvHrSpvQIzeGK, CeMijjiuvHrSpvQIzQjUihH
Example Output:
vHrSpvQIz