instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
iUtNuU, iKtNWk
answer:
tN


question:
GFhJafTV, waHhJaji
answer:
hJa


question:
LiVYEWeXVomYcfKSuz, XhGiREWeXVomwcEKFUN
answer:

EWeXVom