instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
DUhUbmfLuOFAQann, kwnzfLuOFAErR
answer:
fLuOFA


question:
CCzKRbuEAmN, qTLzKRbuhEqq
answer:
zKRbu


question:
RVxtBmCccerZfCXUmKgQxjr, GrDKEOVpMtBmCccerZfFR
answer:

tBmCccerZf