user: Question: What's the distance of the course of stage 4?
Columns: ['Stage', 'Date', 'Course', 'Distance', 'Winner', 'Race Leader']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1', '10 May', 'Milan to Mantua', 'km (mi)', 'Learco Guerra ( ITA )', 'Learco Guerra ( ITA )']
SQL:

assistant: SELECT "Distance" FROM "Table" WHERE "Stage" = '4';