user: Question: What is the smallest crowd of the away team that scored 12.9 (81)?
Columns: ['Home team', 'Home team score', 'Away team', 'Away team score', 'Venue', 'Crowd', 'Date']
Types: ['text', 'text', 'text', 'text', 'text', 'real', 'text']
Sample row: ['Collingwood', '25.19 (169)', 'Hawthorn', '8.16 (64)', 'Victoria Park', 22903.0, '30 June 1979']
SQL:

assistant: SELECT MIN("Crowd") FROM "Table" WHERE "Away team score" = '12.9 (81)';