Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
what is the minimum stage where mountains classification is aitor osa and aitor gonzález won?

### Inputs:
table_name: table, columns: ['Stage', 'Winner', 'General classification', 'Points classification', 'Mountains classification', 'Combination classification', 'Team classification']

### Response:
SELECT MIN Stage FROM table WHERE Mountains classification = Aitor Osa AND Winner = Aitor González