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

Ex Input:
fWJdaAfOCfejXZvidHM, gOpfOCfejXZbtLvSLZI

Ex Output:
fOCfejXZ


Ex Input:
ZRjPgqbLL, uIsmPgqbBB

Ex Output:
Pgqb


Ex Input:
CGXOkDrESTB, jvGOkDrESgwsrt

Ex Output:

OkDrES