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: METHOD : One hundred twelve subjects ( 70 % male ; mean age = 23 . 3 years [ SD = 5 . 1 ] ) with first - episode schizophrenia ( 75 % ) , schizophreniform disorder ( 17 % ) , or schizoaffective disorder ( 8 % ) were randomly assigned to treatment with olanzapine ( 2 . 5 - 20 mg / day ) or risperidone ( 1 - 6 mg / day ) .
### Output Text:
METHOD : One hundred twelve subjects ( 70 % male ; mean age = 23 . 3 years [ SD = 5 . 1 ] ) with first - episode schizophrenia ( 75 % ) , schizophreniform disorder ( 17 % ) , or schizoaffective disorder ( 8 % ) were randomly assigned to treatment with <span class="chemical">olanzapine</span> ( 2 . 5 - 20 mg / day ) or <span class="chemical">risperidone</span> ( 1 - 6 mg / day ) . 