instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
biAihydBoNlzR, IAloNhydBolwUz
answer:
hydBo


question:
sRpnJlgECTHh, JXfmNJlgECKyry
answer:
JlgEC


question:
nQdoQDOfd, UWEoQDkt
answer:

oQD