21137
Amid the heavy snow , Beijing saw a smooth flow of traffic , with no gridlock or serious traffic accidents being reported after the snow storm that caused traffic chaos on the 4th .
 Beijing
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 Beijing