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

Example Input: hCRsCCOoLMpjXwI, lVRCOoLMpxaYFbY
Example Output: COoLMp

Example Input: srPyjmTQhdFFMcQ, QQGBdtyjmTQhmfEy
Example Output: yjmTQh

Example Input: rQWjNwqoEfPxPnu, mapdQNwqoEfcsWa
Example Output:
NwqoEf