In this task, you are given a sentence. You are expected to recognize the name of any form of chemical substances. Although there might be several correct answers, you need to write one of them.

Example Input: COX-1 and COX-2 inhibition in horse blood by phenylbutazone, flunixin, carprofen and meloxicam: an in vitro analysis.
Example Output: carprofen

Example Input: Fragment-based design, synthesis, and biological evaluation of N-substituted-5-(4-isopropylthiophenol)-2-hydroxynicotinamide derivatives as novel Mcl-1 inhibitors.
Example Output: N-substituted-5-(4-isopropylthiophenol)-2-hydroxynicotinamide

Example Input: Hybrid carbon nanotube networks as efficient hole extraction layers for organic photovoltaics.
Example Output:
carbon