instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
QvtDqzQiSknPbRCG, hVxHdqzQiSknPbumdpNIf
answer:
qzQiSknPb


question:
ahPbomjSH, rBbomynK
answer:
bom


question:
ZnqTlvLVywR, WJqrlvLVygJe
answer:

lvLVy