instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
jinzsW, SMnzaW
answer:
nz


question:
CiElmOvTqJGVJkfSaDRzE, EjDJwMyxTvTqJGVJkfluB
answer:
vTqJGVJkf


question:
YQSpPb, OOSpBB
answer:

Sp