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

pYmzRnGPQVPrqPApKTyvaO, tNGPQVPrqPVTh
GPQVPrqP

CzkPtkpMTDeNZwCPbJJn, HzpMVDeNZwCPbJVOU
DeNZwCPbJ

tGWzzFoQhxyyQLqPaoRyX, bzDQhxyyQLsRJm

QhxyyQL