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

Ex Input:
CxosNa, ikosdx

Ex Output:
os


Ex Input:
wXGerDNhSNnCCedyzskswVnh, BfFNhSNnCCedybrUbI

Ex Output:
NhSNnCCedy


Ex Input:
FBdMjhCb, EWdMjCLi

Ex Output:

dMj