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

sJRFPufsaWXNeu, AePufsafc
Pufsa

AuSFmN, crSFXM
SF

JIsqyFaaQrTJKjWx, gXBYyJfsqyFaaQJublaz

sqyFaaQ