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

nrIHKzJCdAQzUDRBYpg, JDzJCdAQzUMMYrLcfO
zJCdAQzU

DQBpdnwVDcnCDEWpD, gAtCdnwVDcnCYv
dnwVDcnC

nGzQppb, qcdzQpdBC

zQp