user: Question: What is the quantity for railway 263?
Columns: ['Class', 'Railway number(s)', 'Quantity', 'Year(s) of manufacture', 'Axle arrangement']
Types: ['text', 'text', 'real', 'text', 'text']
Sample row: ['None', '26–29 ( de )', 4.0, '1853', '2A n2']
SQL:

assistant: SELECT "Quantity" FROM "Table" WHERE "Railway number(s)" = '263';