Among the competitors with age ranges 24 and below, calculate the difference between the number of competitors who weighed greater than 70 kg and competitors who weighted less than 70 kg.
SUBTRACT(COUNT(weight > 70), COUNT(weight < 70)) where age < 24;
SELECT COUNT(CASE WHEN T1.weight > 70 THEN 1 ELSE NULL END) - COUNT(CASE WHEN T1.weight < 70 THEN 1 ELSE NULL END) FROM person AS T1 INNER JOIN games_competitor AS T2 ON T1.id = T2.person_id WHERE T2.age < 24
database name:db_id olympics
city table city Cols: id dtype integer, city name dtype text, 
games table games Cols: id dtype integer, games year dtype integer, games name dtype text, season dtype text, 
games_city table games_city Cols: games id dtype integer, city id dtype integer, 
medal table medal Cols: id dtype integer, medal name dtype text, 
noc_region table noc_region Cols: id dtype integer, noc dtype text, region name dtype text, 
person table person Cols: id dtype integer, full name dtype text, gender dtype text, height dtype integer, weight dtype integer, 
games_competitor table games_competitor Cols: id dtype integer, games id dtype integer, person id dtype integer, age dtype integer, 
person_region table person_region Cols: person_id dtype integer, region_id dtype integer, 
sport table sport Cols: id dtype integer, sport name dtype text, 
event table event Cols: id dtype integer, sport id dtype integer, event name dtype text, 
competitor_event table competitor_event Cols: event id dtype integer, competitor id dtype integer, medal id dtype integer, 
