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

Ex Input:
CkZOSZevST, bbZOSZIg

Ex Output:
ZOSZ


Ex Input:
ksRxEVrz, cOMRxEViwF

Ex Output:
RxEV


Ex Input:
ICizmXnKMpUH, oDrnmXnKgWXX

Ex Output:

mXnK