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

Ex Input:
YXsgPE, ENsgSO

Ex Output:
sg


Ex Input:
bOvlVNWf, iivlVzWt

Ex Output:
vlV


Ex Input:
NSViaUecAakNRPirYCziGbm, LqfjQVAHKoUecAakNRPiRpJcyZJjp

Ex Output:

UecAakNRPi