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: Effect of nondopaminergic drugs on L - dopa - induced dyskinesias in MPTP - treated monkeys .
### Output Text:
Effect of nondopaminergic drugs on <span class="chemical">L - dopa</span> - induced dyskinesias in <span class="chemical">MPTP</span> - treated monkeys . 