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

Example Input: SsshKSaCuNzXzSTgVc, DNNYLWahKSaCuNzXnAjtq
Example Output: hKSaCuNzX

Example Input: UovaYpHjYSQzrfsxRfvIZE, pUOFxIKOGQzrfsxRfvIjrza
Example Output: QzrfsxRfvI

Example Input: yjoJzBGdwfOhsceoOpoap, uSLMdBGdwfOhsIQHBijd
Example Output:
BGdwfOhs