instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
IQIHqbEhpVuNATp, GIJIHqbEhpzWb
answer:
IHqbEhp


question:
yQCDWefwvrPP, RwoMDWefwhSxTR
answer:
DWefw


question:
DpvhISlij, BahISKjn
answer:

hIS