Find the destination of the airport least number of routes in china?
select t1.name from airports as t1 join routes as t2 on t1.apid = t2.dst_apid where t1.country = 'China' group by t1.name order by count ( * ) asc limit 1
how many airports in the list?
select distinct ( count ( name ) ) from airports
how many country in the list?
select count ( distinct country ) from airports