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

Example Input: euQWhCovKplukMYznXcD, XAfMhKdzhCovKplukMcMlSuBw
Example Output: hCovKplukM

Example Input: EeUODjkxsQeTSNsHYpBKIUvEuAKhB, SrpZeTSNsHYpBKdhPFlgMh
Example Output: eTSNsHYpBK

Example Input: pXwjhn, lLwjdO
Example Output:
wj