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

Example Input: DZfOjrQffR, CXOjrQQc
Example Output: OjrQ

Example Input: xzMUdHcoYJFWLOILjrg, vCscoYJFWLzO
Example Output: coYJFWL

Example Input: LoRhvzfyTZlJMqg, nUrrYOdRhvzfyTmr
Example Output:
RhvzfyT