6039
In 2002 the government merged the nine largest airlines into three regional groups based in Beijing Shanghai and  Guangzhou  respectively : Air China China Eastern Airlines and  China Southern Airlines  which operate most of China's external flights .
 city of headquarters: Guangzhou, China Southern Airlines
Given a phrase that describes the relationship between two words, extract the words and the lexical relationship between them. The output format should be "relation1: word1, word2; relation2: word3, word4". 
Option: cities of residence, top members employees, members, alternate names, origin, state or provinces of residence, title of person, spouse, city of headquarters, NA, founded by, state or province of headquarters, employee of, countries of residence, country of birth, founded, subsidiaries, country of headquarters 
Text: {0} 
Answer:
 city of headquarters: Guangzhou, China Southern Airlines