user: Question: What is the highest silver that has 57 as the total, with a bronze greater than 20?
Columns: ['Rank', 'Nation', 'Gold', 'Silver', 'Bronze', 'Total']
Types: ['real', 'text', 'real', 'real', 'real', 'real']
Sample row: [1.0, 'Soviet Union (URS)', 33.0, 29.0, 26.0, 88.0]
SQL:

assistant: SELECT MAX("Silver") FROM "Table" WHERE "Total" = 57.0 AND "Bronze" > 20.0;