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In 2004 , he became a director of Berkshire Hathaway , the investment company headed by long-time friend Warren Buffett .
 organization: Berkshire Hathaway; person: Warren Buffett
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 organization: Berkshire Hathaway; person: Warren Buffett