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

Example Input: wXGerDNhSNnCCedyzskswVnh, BfFNhSNnCCedybrUbI
Example Output: NhSNnCCedy

Example Input: XmiLktrUjJDOCJ, UIKrUjJDOQsR
Example Output: rUjJDO

Example Input: qVuuiqrcULxslJriD, ppDYlFduiqrcULxslAWM
Example Output:
uiqrcULxsl