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

Ex Input:
DQBpdnwVDcnCDEWpD, gAtCdnwVDcnCYv

Ex Output:
dnwVDcnC


Ex Input:
ptVlCwpfOZIi, QEdyVlCwpfOwp

Ex Output:
VlCwpfO


Ex Input:
RgshbwENOalLTSvrKeFpmV, qqOalLTSvrTiIt

Ex Output:

OalLTSvr