Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE city ( city VARCHAR, regional_population INTEGER )

### Question ###
Please give me a list of cities whose regional population is over 8000000 or under 5000000.

### Accurate SQL ###

SELECT city FROM city WHERE regional_population > 10000000 UNION SELECT city FROM city WHERE regional_population < 5000000