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

Example Input: pBDnbfrAxJfVhPBxheXZGp, LMtorAxJfVhPnnaed
Example Output: rAxJfVhP

Example Input: mjCEUoPmeKbvCgUtUL, SrHtrPmeKbvYpQAVp
Example Output: PmeKbv

Example Input: nFlCkEdsSs, hODrlCkEiPOg
Example Output:
lCkE