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He challenged seven other swimmers on the second heat , including Olympic veterans Derya Büyükuncu of Turkey and Nicholas Neckles of Barbados .
 Derya Büyükuncu, Nicholas Neckles
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Derya Büyükuncu, Nicholas Neckles