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

Ex Input:
UovaYpHjYSQzrfsxRfvIZE, pUOFxIKOGQzrfsxRfvIjrza

Ex Output:
QzrfsxRfvI


Ex Input:
YXsgPE, ENsgSO

Ex Output:
sg


Ex Input:
qGtntTpd, AFdtntZrW

Ex Output:

tnt