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: Show the number of cities in counties that have a population more than 20000. | county_public_safety : county_id , name , population , police_officers , residents_per_officer , case_burden , crime_rate , police_force , location | city : city_id , county_id , name , white , black , amerindian , asian , multiracial , hispanic | city.county_id = county_public_safety.county_id | 

### Response:

select count ( _ ) from _ where _ in ( select _ from _ where _ ) | select count ( * ) from city where county_id in ( select county_id from county_public_safety where population > 20000 )