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

Ex Input:
DUhUbmfLuOFAQann, kwnzfLuOFAErR

Ex Output:
fLuOFA


Ex Input:
SyweIt, ILweip

Ex Output:
we


Ex Input:
cyAuQNEQYRLwvBwnEqNcTqoEpq, kJQcRLwvBwnEqNYeVfYvGDy

Ex Output:

RLwvBwnEqN