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

Example Input: JAfPtjqqUYMD, cpXItjqqFN
Example Output: tjqq

Example Input: bOvlVNWf, iivlVzWt
Example Output: vlV

Example Input: hYSEErmdZmPXSpdUu, KAarrmdZmPXSpdfYaVQEEA
Example Output:
rmdZmPXSpd