user: Question: How many mountains classifications when Rui Costa is the winner?
Columns: ['Stage', 'Winner', 'General classification', 'Points classification', 'Mountains classification', 'Young rider classification', 'Team classification', 'Combativity award']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'Philippe Gilbert', 'Philippe Gilbert', 'Philippe Gilbert', 'Philippe Gilbert', 'Geraint Thomas', 'Omega Pharma-Lotto', 'Perrig Quemeneur']
SQL:

assistant: SELECT COUNT("Mountains classification") FROM "Table" WHERE "Winner" = 'Rui Costa';