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:
sRpnJlgECTHh, JXfmNJlgECKyry

Ex Output:
JlgEC


Ex Input:
WrPZli, vmPZcs

Ex Output:

PZ