instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
wbdHVigIkjNkuAmbr, iSgIkjNkQYyn
answer:
gIkjNk


question:
oWwqraAz, uxTqraonu
answer:
qra


question:
obTZdL, VCTZoE
answer:

TZ