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: UovaYpHjYSQzrfsxRfvIZE, pUOFxIKOGQzrfsxRfvIjrza
Example Output: QzrfsxRfvI

Example Input: PdmpPgzQyMiUyZiFnUXaq, qrYnqusTpPgzQyMiUHyXVMMuo
Example Output:
pPgzQyMiU