In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
--------
Question: AuSFmN, crSFXM

Answer: SF


Question: zBxuZfJgYrlRSzkmAktO, YNMgYrlRSzklmBOH

Answer: gYrlRSzk


Question: bLfksSdHDdztEdnAEVuwCXI, TmCtjUHDdztEdnADClQZ

Answer:
HDdztEdnA