8500
The chemical universe database GDB - 17 contains 166 . 4 billion molecules of up to 17 atoms of C , N , O , S , and halogens obeying rules for chemical stability , synthetic feasibility , and medicinal chemistry .
 Chemical: C; Chemical: N; Chemical: O; Chemical: S; Chemical: halogens
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: C; Chemical: N; Chemical: O; Chemical: S; Chemical: halogens