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: We studied two groups of Parkinson ' s disease patients with ( Parkinson ' s disease + LID , n = 23 ) and without levodopa - induced dyskinesias ( Parkinson ' s disease - LID , n = 10 ) , and age - matched healthy controls .
### Output Text:
We studied two groups of Parkinson ' s disease patients with ( Parkinson ' s disease + LID , n = 23 ) and without <span class="chemical">levodopa</span> - induced dyskinesias ( Parkinson ' s disease - LID , n = 10 ) , and age - matched healthy controls . 