user: Question: What is the Distance of the 1945 Vuelta a Espana with 4a Stage?
Columns: ['Stage', 'Date', 'Course', 'Distance', 'Winner']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['1', '10 May', 'Madrid – Salamanca', 'km (mi)', 'Julián Berrendero ( ESP )']
SQL:

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