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

Ex Input:
CUxfOt, dyxfNp

Ex Output:
xf


Ex Input:
CMrTXnTnTVaR, srnXnTnTDNULO

Ex Output:
XnTnT


Ex Input:
lOlVOCd, ZKblVOvRR

Ex Output:

lVO