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

Ex Input:
kvutZfcPKzHE, kTKutZfcPTGmU

Ex Output:
utZfcP


Ex Input:
BVipiZoGXaWdjmDsxWP, yxppsiYkiZoGXaWdjoDRuKW

Ex Output:
iZoGXaWdj


Ex Input:
RRsAun, PBsAIk

Ex Output:

sA