instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
cZSEmdgP, YsSEmEIM
answer:
SEm


question:
rvLoiycpZw, idcvoiycpcLyD
answer:
oiycp


question:
WADlqxnRHDY, iaeKqxnRvJ
answer:

qxnR


