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

GBTHKtWUzK, ovVNKtWUmVJF
KtWU

zBxuZfJgYrlRSzkmAktO, YNMgYrlRSzklmBOH
gYrlRSzk

UjNlhc, SyNlTK

Nl