instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
uqazNuZhdJhw, KbnrzNuZhBdp
answer:
zNuZh


question:
wbdHVigIkjNkuAmbr, iSgIkjNkQYyn
answer:
gIkjNk


question:
kZtGHpS, cGUtGHUAW
answer:

tGH