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

[Q]: VLxrvK, gvxrac
[A]: xr


[Q]: UovaYpHjYSQzrfsxRfvIZE, pUOFxIKOGQzrfsxRfvIjrza
[A]: QzrfsxRfvI


[Q]: VZHMmH, IfHMoE
[A]:
HM