instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
iJbjApY, ggwbjAws
answer:
bjA


question:
bUcuzFgsdfojVR, IdcuzFgsdMRgtMA
answer:
cuzFgsd


question:
ZpZzELEv, xkzELTfW
answer:

zEL