instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
nxoXDohHr, WcbkXDohFbJ
answer:
XDoh


question:
dReySjyqecU, loSjyqiRl
answer:
Sjyq


question:
LFbInNUcqxAKsDyy, VpBdSVanNUcqxAfoh
answer:

nNUcqxA