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:
3-Hydroxypyridin-2-thione as Novel Zinc Binding Group for Selective Histone Deacetylase Inhibition.

Ex Output:
Zinc


Ex Input:
Sulfasalazine, a potent suppressor of lymphoma growth by inhibition of the x(c)- cystine transporter: a new action for an old drug.

Ex Output:
cystine


Ex Input:
Nuclear receptors in bile acid metabolism.

Ex Output:

bile acid