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

Ex Input:
kWnjCoVmCSVuW, RILPKCoVmCSVbaOza

Ex Output:
CoVmCSV


Ex Input:
BrDGrTD, PBHDGrDw

Ex Output:
DGr


Ex Input:
UZhPooIz, NjKhPoozw

Ex Output:

hPoo