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:
lLxXqKscqizXTO, TqrKscqizutDudo
answer:
Kscqiz


question:
QmbdQv, WWbdBI
answer:

bd