user: Question: How many Mountains Classifications were in the race with Mike Northey as Youth Classification?
Columns: ['Stage', 'Winner', 'General classification', 'Mountains classification', 'Points classification', 'Youth classification', 'Team Classification']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'Tom Zirbel', 'Tom Zirbel', 'Tom Zirbel', 'Tom Zirbel', 'Nick Frey', 'Bissell']
SQL:

assistant: SELECT COUNT("Mountains classification") FROM "Table" WHERE "Youth classification" = 'Mike Northey';