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: Cerebral infarction occurred in 10 patients ( 22 % ) , intracerebral hemorrhage in 22 ( 49 % ) , and subarachnoid hemorrhage in 13 ( 29 % ) .
### Output Text:
Cerebral infarction occurred in 10 patients ( 22 % ) , intracerebral hemorrhage in 22 ( 49 % ) , and subarachnoid hemorrhage in 13 ( 29 % ) . 