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

Ex Input:
rcKVmDzwJKeK, uYqmDzwJKxkGi

Ex Output:
mDzwJK


Ex Input:
BpGFyhLez, DfFyhuJY

Ex Output:
Fyh


Ex Input:
kjZrwPEx, fmZrwkwp

Ex Output:

Zrw