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

[Q]: QlJnxO, BLJnCQ
[A]: Jn


[Q]: fWJdaAfOCfejXZvidHM, gOpfOCfejXZbtLvSLZI
[A]: fOCfejXZ


[Q]: SGXxYukB, XjXxYuOAzY
[A]:
XxYu