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: AIM : Hemorrhagic cystitis ( HC ) is a limiting side - effect of chemotherapy with ifosfamide ( IFS ) .
### Output Text:
AIM : Hemorrhagic cystitis ( HC ) is a limiting side - effect of chemotherapy with <span class="chemical">ifosfamide</span> ( <span class="chemical">IFS</span> ) . 