What is the fastest way to get from Guangzhou to Nanjing? How long does it take?

Hello, from Guangzhou to Nanjing, there are many means of transportation, the fastest is to take the plane, but relatively speaking, it will be more expensive, there are trains and automobiles, automobiles than the train to be close to more than 5 hours, if you are not in a hurry, I would recommend that you take the train is safer, the bus is not very safe and the air inside the compartment is not very good;