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

HKCoXQsLRtowYJ, PGRzNUQsLRtoLcqkn
QsLRto

SeXNqRAbKdLuWXgb, npsIWRAbKdLuUWSbvuS
RAbKdLu

PVvnIOZGttoNhIYDeEaamKcAo, AxttoNhIYDeDSUEF

ttoNhIYDe