instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
rduIwWNGM, AJqYIwWNaCap
answer:
IwWN

question:
DwkTGsIXLfmjMV, VqRlMxtsSBkTGsIXLfmjbvI
answer:
kTGsIXLfmj

question:
ZzzQrFdO, GDIHzQrFik
answer:
zQrF