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

[Q]: MvALRGKkpALcKdhTtnm, neMkRGKkpALcKdcaxnXEPxW
[A]: RGKkpALcKd


[Q]: XeQwOS, OuQwNR
[A]: Qw


[Q]: eJpUdACuXHAc, PoOWBRdACuXHwtRV
[A]:
dACuXH