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

Ex Input:
CwTYJWQbzEZkvcqKn, hBnhJWQbzEZkKmVM

Ex Output:
JWQbzEZk


Ex Input:
sEYtoQlG, XIstoQQPw

Ex Output:
toQ


Ex Input:
qavOWPGVGswTjpqSD, NbgHEjPGVGswjKm

Ex Output:

PGVGsw