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Internationally , the largest ( " Big Five " ) advertising-agency groups are Dentsu , Interpublic , Omnicom , Publicis , and WPP .
 Dentsu, Interpublic, Omnicom, Publicis, WPP
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Dentsu, Interpublic, Omnicom, Publicis, WPP