instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
SIIPePlrkftKkzfgdjg, JqNnXHrkftKkzOMUwmc
answer:
rkftKkz


question:
vJtmxQmHEq, yobgAtmxQmMeoLz
answer:
tmxQm


question:
pJfLBkhOsL, fcBkhOxr
answer:

BkhO