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

Ex Input:
PIcbiJj, hedcbiZHF

Ex Output:
cbi


Ex Input:
FgQsxN, UMQsIa

Ex Output:
Qs


Ex Input:
MXFLsfwVJeJkRhRX, PeBCtKQwVJeJkRhvwgCX

Ex Output:

wVJeJkRh