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

Example Input: vMsEJRoLkWcmkuwNRz, ZmoLkWcmVZiBv
Example Output: oLkWcm

Example Input: bUcuzFgsdfojVR, IdcuzFgsdMRgtMA
Example Output: cuzFgsd

Example Input: NEOAgUaRiMJon, zzlbtgUaRiMiRuJ
Example Output:
gUaRiM