instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
zmbmQuyNGOe, mUMEmQuyiuS
answer:
mQuy

question:
CiTNsbepy, DFNsbeZl
answer:
Nsbe

question:
JlGejAa, cjGejhG
answer:
Gej