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Greg Nixon ( born September 12 , 1981 ) is an American sprinter who specialises in the 400 meters .
 person: Greg Nixon; location: American
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 person: Greg Nixon; location: American