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: CONCLUSION : Olanzapine demonstrated greater efficacy than placebo in the treatment of acute bipolar mania and was generally well tolerated .
### Output Text:
CONCLUSION : <span class="chemical">Olanzapine</span> demonstrated greater efficacy than placebo in the treatment of acute bipolar mania and was generally well tolerated . 