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

YXsgPE, ENsgSO
sg

lPhVhAQZWJDrvzcEaGEwKgZAuJI, qIJDrvzcEaGDRCRrB
JDrvzcEaG

UlERlmTCKG, xffbERlmVUF

ERlm