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

Example Input: eedZoMwKgDhdsgs, kMMwKgDLm
Example Output: MwKgD

Example Input: oHoJrr, YAoJSq
Example Output: oJ

Example Input: PmJHTQJfSWrnAWEjAK, KncxmyJfSWrnAWEjbL
Example Output:
JfSWrnAWEj