user: Question: Name the total number of years for chassis of maserati 250f and points less than 0
Columns: ['Year', 'Entrant', 'Chassis', 'Engine', 'Points']
Types: ['real', 'text', 'text', 'text', 'real']
Sample row: [1955.0, 'Scuderia Volpini', 'Arzani-Volpini', 'Maserati Straight-4', 0.0]
SQL:

assistant: SELECT COUNT("Year") FROM "Table" WHERE "Chassis" = 'maserati 250f' AND "Points" < 0.0;