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

Ex Input:
KTAFonizDqCVvucpJWrItdw, rfFonizDqCVvYbGhb

Ex Output:
FonizDqCVv


Ex Input:
atDgsOWuP, UJMgsOrwj

Ex Output:
gsO


Ex Input:
xukVXlsRuFjFa, bSqGkMXlsRuFjSElIrfk

Ex Output:

XlsRuFj