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

Example Input: oiNEYHxbvAb, bcDDdEYHxbCREd
Example Output: EYHxb

Example Input: trHTzJpm, aCHTzVVA
Example Output: HTz

Example Input: dLQzHPTk, SMhQzHPOI
Example Output:
QzHP