CREATE TABLE airports (apid VARCHAR)
CREATE TABLE routes (dst_apid VARCHAR)

Find the number of routes whose destination airports are in Canada.
SELECT COUNT(*) FROM airports AS T1 JOIN routes AS T2 ON T1.apid = T2.dst_apid WHERE country = 'Canada'
SELECT COUNT(*) FROM "airports" AS "T1" JOIN "routes" AS "T2" ON "T1"."apid" = "T2"."dst_apid" WHERE "country" = 'Canada'