232380
In 1950 there were 86 cities in the world with a population over one million , today there are 400 , and by 2015 , there will be at least 550 . "
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities:  
Answer:
 None