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: Patients with aneurysmal subarachnoid hemorrhage ( SAH ) were randomized to receive either ketoprofen , 100 mg , three times a day ( ketoprofen group , n = 9 ) or a weak NSAID , acetaminophen , 1 g , three times a day ( acetaminophen group , n = 9 ) starting immediately after the diagnosis of aneurysmal SAH .
### Output Text:
Patients with aneurysmal subarachnoid hemorrhage ( SAH ) were randomized to receive either <span class="chemical">ketoprofen</span> , 100 mg , three times a day ( <span class="chemical">ketoprofen</span> group , n = 9 ) or a weak NSAID , <span class="chemical">acetaminophen</span> , 1 g , three times a day ( <span class="chemical">acetaminophen</span> group , n = 9 ) starting immediately after the diagnosis of aneurysmal SAH . 