instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
XSnVeAjWLFWTgwmf, WsByLAjWLFWnQfl
answer:
AjWLFW


question:
ykDpbd, YFDpmO
answer:
Dp


question:
zqwhMdAdXQfQCAmVNaYZm, toYMIwQeadAdXQfQCAmLyheFOv
answer:

dAdXQfQCAm