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

Ex Input:
RyaNyUvXAaZHLXUtYuz, CkbsWxZyUvXAaZHLXJJzugDy

Ex Output:
yUvXAaZHLX


Ex Input:
XbjDHRCWxdPbhibUKn, SrpuPDHRCWxdPbKPWEXNWbZ

Ex Output:
DHRCWxdPb


Ex Input:
QalARBKstZQuZMaof, pgLfrVdWKstZQuZMaeP

Ex Output:

KstZQuZMa