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

Example Input: ftvxfhsnJEygzV, JYxSfhsnJnIqkW
Example Output: fhsnJ

Example Input: sUdaWtsiRgqAYHykrHwjyDvZgD, MJdFXYiRgqAYHykrakSGHMr
Example Output: iRgqAYHykr

Example Input: lgFwrPWUdOkYf, yrAbsYYFwrPWUdOLrtFj
Example Output:
FwrPWUdO