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

QRPOwtZATjDoJDdRNNSOH, wiafFMwpAjDoJDdRNNuCDZ
jDoJDdRNN

IobjElBjKvpepE, kRulBjKvvxU
lBjKv

KVDRlPhZKBkcuMzudaioluBJez, OgTuEIBkcuMzudayolFA

BkcuMzuda