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: Similarly , in patient diaries , although both treatments caused reduction in subjective dyskinesia scores during the days of intervention , the effect was sustained for 3 days after the intervention for the real rTMS only .
### Output Text:
Similarly , in patient diaries , although both treatments caused reduction in subjective dyskinesia scores during the days of intervention , the effect was sustained for 3 days after the intervention for the real rTMS only . 