user: Question: What is the smallest number of seats in a Retired vehicle that was started in service in 1981?
Columns: ['Make', 'Year placed in service', 'Quantity', 'Number of seats', 'Wheelchair accessible? ()', 'Current status']
Types: ['text', 'text', 'real', 'real', 'text', 'text']
Sample row: ['GM " New Look "', '1971, 1972', 132.0, 45.0, 'No', 'Retired; one bus retained for historical purposes']
SQL:

assistant: SELECT MIN("Number of seats") FROM "Table" WHERE "Current status" = 'Retired' AND "Year placed in service" = '1981';