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

Ex Input:
UCbReSfuLcbzmBCl, snQRReSfuLcbzmjqVPSdpp

Ex Output:
ReSfuLcbzm


Ex Input:
qMnjlfIsQRtUlPggCpHqu, gfVndMwYDIsQRtUlPgqBJKCX

Ex Output:
IsQRtUlPg


Ex Input:
fIcYXzovxPBywUmNqtU, RFvxPBywUmdf

Ex Output:

vxPBywUm