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

Ex Input:
RyaNyUvXAaZHLXUtYuz, CkbsWxZyUvXAaZHLXJJzugDy

Ex Output:
yUvXAaZHLX


Ex Input:
OyXwTWbLByC, yODnTWbLWYzc

Ex Output:
TWbL


Ex Input:
krdTaDVSdgRrafYxRBO, pDdgRrafYxBQN

Ex Output:

dgRrafYx