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

[Q]: vSFxjd, AHFxpi
[A]: Fx


[Q]: TvNVpHLPYjBCeUpyxlzFZ, tgKdPKVYjBCeUpyPK
[A]: YjBCeUpy


[Q]: AKqjLFtQuaBzdYr, pBIjLFtQuaLBquWG
[A]:
jLFtQua