17056
We employed a cross - sectional design to compare 31 cocaine - na i ve participants , 35 occasional cocaine users and 20 regular recreational cocaine users .
 Chemical: cocaine; Chemical: cocaine; Chemical: cocaine
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: cocaine; Chemical: cocaine; Chemical: cocaine