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: In this study we investigated tolerability and reliability of nimesulide and paracetamol in a very large number of patients with an exclusive well - documented history of NSAID - induced urticaria / angioedema .
### Output Text:
In this study we investigated tolerability and reliability of <span class="chemical">nimesulide</span> and <span class="chemical">paracetamol</span> in a very large number of patients with an exclusive well - documented history of <span class="chemical">NSAID</span> - induced urticaria / angioedema . 