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

[Q]: NwmTIZSnlKGG, qAYIZSnfWRd
[A]: IZSn


[Q]: PivhPfah, XSghPfOi
[A]: hPf


[Q]: AQiXXtCukq, GFjziXXtGos
[A]:
iXXt