In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Sub - chronic inhibition of nitric - oxide synthesis modifies haloperidol - induced catalepsy and the number of NADPH - diaphorase neurons in mice .
### Output Text:
Sub - chronic inhibition of <span class="chemical">nitric - oxide</span> synthesis modifies <span class="chemical">haloperidol</span> - induced catalepsy and the number of <span class="chemical">NADPH</span> - diaphorase neurons in mice . 