instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
STvKOHq, XMGvKOdyM
answer:
vKO


question:
gTjTwC, OUjTgM
answer:
jT


question:
ADjhiuu, hUjhiDK
answer:

jhi