user: Question: What was the lowest city population for the district of rajanpur district with a area of 6 km squared and a serial number less than 29?
Columns: ['Serial No.', 'District', 'Headquartered City', 'City Population (2009)', 'City Area(km 2 )']
Types: ['real', 'text', 'text', 'real', 'real']
Sample row: [1.0, 'Attock District', 'Attock City', 94620.0, 20.0]
SQL:

assistant: SELECT MIN("City Population (2009)") FROM "Table" WHERE "City Area(km 2 )" = 6.0 AND "District" = 'rajanpur district' AND "Serial No." < 29.0;