user: Question: What is the capacity for the stadium of Kadrioru Stadium and a current manager of Sergei Ratnikov?
Columns: ['Club', 'Location', 'Stadium', 'Capacity', 'Current manager']
Types: ['text', 'text', 'text', 'real', 'text']
Sample row: ['Flora', 'Tallinn', 'A. Le Coq Arena', 9300.0, 'Pasi Rautiainen']
SQL:

assistant: SELECT "Capacity" FROM "Table" WHERE "Stadium" = 'Kadrioru Stadium' AND "Current manager" = 'Sergei Ratnikov';