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

Ex Input:
OyXwTWbLByC, yODnTWbLWYzc

Ex Output:
TWbL


Ex Input:
faHRBWyXsYzYmHQyy, aHTyXsYzYeXBFV

Ex Output:
yXsYzY


Ex Input:
MrCHIRKGtuW, sFRIRKGuvq

Ex Output:

IRKG