There is a centenarian named Sun in Beijing, born in 19 13. Master Sun is a strange man. Strangely, people who lived 100 years old or older have not all white hair, and about half of them have black hair. Old people have a special diet hobby. Simply put, they usually like to eat "white with black". This "white plus black" is not the kind of medicine that has been advertised. Old Sunman ate it. This is a real organic food. White is actually sweet potato, and some places are called sweet potato. Black is actually black sesame. Master Sun has a history of eating sweet potatoes. Especially in difficult times, people often rely on sweet potatoes to satisfy their hunger. Many people who have come from difficult times have been injured by eating sweet potatoes and have a feeling of "vomiting at the sight of sweet potatoes"; No matter whether the living conditions are good or bad, Master Sun always likes to eat sweet potatoes. The old man loves to eat baked sweet potatoes, and his children specially bought him an oven, cooked it themselves and baked it often.