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:
txJhzNeBj, qLJhzNesV
answer:
JhzNe


question:
qkUzcMIIAzOyE, nxSulcMIIAdwqH
answer:

cMIIA