In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.

[Q]: zBNTHKtofMdHfBgJhOfojzM, VIkVdFapofMdHfBgjPCUo
[A]: ofMdHfBg


[Q]: ChKUlYUTQQBjZMZkgEed, lmQQBjZMZkgdEf
[A]: QQBjZMZkg


[Q]: TVdfOs, iDdfBv
[A]:
df