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

Ex Input:
jinzsW, SMnzaW

Ex Output:
nz


Ex Input:
QgkpBHsrfRYJCa, AdjbKLpBHsrfbpBC

Ex Output:
pBHsrf


Ex Input:
zVtKksluUdpSH, paVksluUdpqsgvV

Ex Output:

ksluUdp