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

Example Input: wlFcxOHoXC, IWFcxOIWTk
Example Output: FcxO

Example Input: ftvxfhsnJEygzV, JYxSfhsnJnIqkW
Example Output: fhsnJ

Example Input: rqbKcIqpIH, VloXKcIqvIMi
Example Output:
KcIq