CREATE TABLE routes (rid DECIMAL, dst_apid DECIMAL, dst_ap TEXT, src_apid DECIMAL, src_ap TEXT, alid DECIMAL, airline TEXT, codeshare TEXT)
CREATE TABLE airports (apid DECIMAL, name TEXT, city TEXT, country TEXT, x DECIMAL, y DECIMAL, elevation DECIMAL, iata TEXT, icao TEXT)
CREATE TABLE airlines (alid DECIMAL, name TEXT, iata TEXT, icao TEXT, callsign TEXT, country TEXT, active TEXT)

How many cities are there that have more than 3 airports?
SELECT COUNT(*) FROM (SELECT city FROM airports GROUP BY city HAVING COUNT(*) > 3)
WITH "cte" AS (SELECT 1 AS "_" FROM "airports" GROUP BY "city" HAVING COUNT(*) > 3) SELECT COUNT(*) FROM "cte" AS "cte"