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

Ex Input:
oZNKLmfxecDfkXEGFkRBYk, tReqkiExecDfkXEGtNZpJVRxC

Ex Output:
xecDfkXEG


Ex Input:
wbFDXJQDQxQJzudOUlR, QEbsIDXJQDQxQsSYIutwU

Ex Output:
DXJQDQxQ


Ex Input:
UzZrgAKxKzniAhJLo, fBQxKVAKxKzniYtXCi

Ex Output:

AKxKzni