instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
FCKbAgSVgj, wAEAWbAgSVSVwD
answer:
bAgSV


question:
VpJvIZdkzKovjc, BZEizZdkzKYZ
answer:
ZdkzK


question:
doEubgGmODQsDSuiSOv, lFdSmODQsDSahr
answer:

mODQsDS