user: Question: Which stage has a mountains classification of Mariano Piccoli and was won by Giuseppe Citterio?
Columns: ['Stage', 'Winner', 'General classification', 'Points classification', 'Mountains classification', 'Trofeo Fast Team']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1', 'Mario Cipollini', 'Mario Cipollini', 'Mario Cipollini', 'Giuseppe Guerini', 'Mercatone Uno-Saeco']
SQL:

assistant: SELECT "Stage" FROM "Table" WHERE "Mountains classification" = 'Mariano Piccoli' AND "Winner" = 'Giuseppe Citterio';