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

Ex Input:
vSFxjd, AHFxpi

Ex Output:
Fx


Ex Input:
eeoJEtGHPDvHck, ezPGHPDvHSf

Ex Output:
GHPDvH


Ex Input:
mDkBaiWqyNgSaAJOBIhXGK, gvHdMJAoyNgSaAJOCjxbmHir

Ex Output:

yNgSaAJO