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

Ex Input:
WjyKtxKtEYjP, vuBZJZyKtxKtXRZs

Ex Output:
yKtxKt


Ex Input:
QzJdafaGRLWEguLkOaw, brmPLBoaGRLWEguEaF

Ex Output:
aGRLWEgu


Ex Input:
HDhkYd, cNhkkb

Ex Output:

hk