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

DnAzbgMtdPKsNCMpBfc, QdfXRkWREzbgMtdPKsGx
zbgMtdPKs

oDdulHNcCdgbRGxiBTxM, kDcCdgbRGnsJlvas
cCdgbRG

tcxnWRDJoFFhAs, SwnWRDJoFtcqvcX

nWRDJoF