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

Example Input: fAsWQxuyBevvLogrSrgg, tmdBEUxuyBevvLogXjiMCbh
Example Output: xuyBevvLog

Example Input: sRpnJlgECTHh, JXfmNJlgECKyry
Example Output: JlgEC

Example Input: rAHSWVhiIRob, ewvWgHSWVhRS
Example Output:
HSWVh