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: The risk and associated factors of methamphetamine psychosis in methamphetamine - dependent patients in Malaysia .
### Output Text:
The risk and associated factors of <span class="chemical">methamphetamine</span> psychosis in <span class="chemical">methamphetamine</span> - dependent patients in Malaysia . 