instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
SQNzngllNbOkKDK, MijfNzngllNDfWge
answer:
NzngllN


question:
oiNEYHxbvAb, bcDDdEYHxbCREd
answer:
EYHxb


question:
btOtoJNxnAS, FyQltoJNxyQ
answer:

toJNx