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: CONCLUSIONS : Overall , these results indicate that this experimental model of CP - induced cystitis may be an interesting new behavioral model of inflammatory visceral pain , allowing a better understanding of these painful syndromes and thus a better therapeutic approach to them .
### Output Text:
CONCLUSIONS : Overall , these results indicate that this experimental model of <span class="chemical">CP</span> - induced cystitis may be an interesting new behavioral model of inflammatory visceral pain , allowing a better understanding of these painful syndromes and thus a better therapeutic approach to them . 