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

Ex Input:
cvZfWOwa, xOfWOhZs

Ex Output:
fWO


Ex Input:
jkGcUm, dxGcSI

Ex Output:
Gc


Ex Input:
dmNYYOKluPSHFz, wJddrNYYOKluPSHtByKHBUK

Ex Output:

NYYOKluPSH