question: If the season is before 2000, the runner up was north melbourne, and it's the pre-season cup, what's the sum of attendees?
answer: SELECT SUM(attendance) FROM table_name_8 WHERE premiership = "pre-season cup" AND runner_up = "north melbourne" AND season < 2000
context: CREATE TABLE table_name_8 (attendance INTEGER, season VARCHAR, premiership VARCHAR, runner_up VARCHAR)