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

Ex Input:
PGjDRPDzGaBR, rpIJRPDzWi

Ex Output:
RPDz


Ex Input:
oKZCAErEMqzODnkcNqxVdoBOC, yHzRJuSqzODnkcNqxExr

Ex Output:
qzODnkcNqx


Ex Input:
WTNvhzvuHUMx, OGclhzvuHUeiXHwN

Ex Output:

hzvuHU