instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
aIZIsqL, wxSZIsEnO
answer:
ZIs


question:
NxgzLSzFGa, JvLzLSzsuj
answer:
zLSz


question:
BDtpHTBGOOCs, pxtZQpHTBGCm
answer:

pHTBG


