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

[Q]: apGMPThLTCw, LvMPThYW
[A]: MPTh


[Q]: qMnjlfIsQRtUlPggCpHqu, gfVndMwYDIsQRtUlPgqBJKCX
[A]: IsQRtUlPg


[Q]: SUYYRN, JvYYKR
[A]:
YY