instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
lOedgdw, aoedgpn
answer:
edg


question:
esIMEOgV, tNIMEybb
answer:
IME


question:
ZbFNjgZQzTERgk, pYwYatjgZQzTmmc
answer:

jgZQzT