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#BREAKING: Obama says U . S . imposing sanctions on Russia in energy , arms and finance sectors . http://t.co/9NRgAQE0wC
 Obama, U . S ., Russia
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Obama, U . S ., Russia