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

[Q]: JIOKyo, oPOKsX
[A]: OK


[Q]: XqyPjqNZDEK, EfwPjqNgjIP
[A]: PjqN


[Q]: PQJLuH, mLJLUh
[A]:
JL