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

Ex Input:
lLxXqKscqizXTO, TqrKscqizutDudo

Ex Output:
Kscqiz

Ex Input:
mvIvSzMtYsfVLdaGEmef, wnzMtYsfVLdaKm

Ex Output:
zMtYsfVLda

Ex Input:
EABsMK, uJBsyb

Ex Output:
Bs