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.

Ex Input:
Synthesis and biological evaluation of some novel resveratrol amide derivatives as potential anti-tumor agents.

Ex Output:
resveratrol amide

Ex Input:
Stable and high-rate overcharge protection for rechargeable lithium batteries.

Ex Output:
lithium

Ex Input:
The accumulation of metal (Co, Cr, Cu, Mn and Zn) in freshwater Ulva (Chlorophyta) and its habitat.

Ex Output:
Mn