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

Ex Input:
oGaGjsaKsUpLQAg, iDGjsaKsUoYGuta

Ex Output:
GjsaKsU


Ex Input:
RMurrwPjlfG, QBKrrwPDkTM

Ex Output:
rrwP


Ex Input:
EcHuDxlowQAertWVJue, xWCLQcpTxlowQAerZBbLX

Ex Output:

xlowQAer