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

Ex Input:
jdLbZSCzaAHGbNwILGmudOH, RdIPuEYJvUZSCzaAHGbNduLToRC

Ex Output:
ZSCzaAHGbN


Ex Input:
RtOkkgLvhgfGlX, vCOkgLvhzOa

Ex Output:
kgLvh


Ex Input:
QePAPpbelJrwDWzoreQRTvBU, LflJrwDWzorHWJWbM

Ex Output:

lJrwDWzor