user: Question: Who's the captain of the team whose stadium is Gradski Stadion?
Columns: ['Club', 'Location', 'Manager', 'Stadium', 'Capacity', 'Team captain']
Types: ['text', 'text', 'text', 'text', 'real', 'text']
Sample row: ['Beroe', 'Stara Zagora', 'Ilian Iliev Category:Articles with hCards', 'Beroe', 17800.0, 'Slavi Zhekov']
SQL:

assistant: SELECT "Team captain" FROM "Table" WHERE "Stadium" = 'Gradski Stadion';