Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.

### Instruction:

Convert text to sql: How many accelerators are not compatible with the browsers listed ? | web_client_accelerator : id , name , operating_system , client , connection | browser : id , name , market_share | accelerator_compatible_browser : accelerator_id , browser_id , compatible_since_year | accelerator_compatible_browser.browser_id = browser.id | accelerator_compatible_browser.accelerator_id = web_client_accelerator.id | 

### Response:

select count ( _ ) from _ where _ not in ( select _ from _ ) | select count ( * ) from web_client_accelerator where id not in ( select accelerator_id from accelerator_compatible_browser )