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

Example Input: CMrTXnTnTVaR, srnXnTnTDNULO
Example Output: XnTnT

Example Input: ZKMRTxCxbsbX, iovHrMRTxCxbsjv
Example Output: MRTxCxbs

Example Input: rMIbScGynmFhuLYpMW, dPYrmOynmFhuLYpjRFyqzmc
Example Output:
ynmFhuLYp