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

[Q]: QeNePjbLBKbDOuAVTJtXL, xjPVOyPbLBKbDOuDsMSEF
[A]: bLBKbDOu


[Q]: HKCoXQsLRtowYJ, PGRzNUQsLRtoLcqkn
[A]: QsLRto


[Q]: zsBxTs, xlBxCW
[A]:
Bx