user: Question: What are the smallest assets with a Company of piraeus bank, and a Revenue (US$ billion) smaller than 3.9?
Columns: ['Rank', 'Company', 'Revenues (US$ billion)', 'Profit (US$ billion)', 'Assets (US$ billion)', 'Market value (US$ billion)']
Types: ['real', 'text', 'real', 'real', 'real', 'real']
Sample row: [1.0, 'National Bank of Greece', 10.4, 16.0, 137.0, 1.0]
SQL:

assistant: SELECT MIN("Assets (US$ billion)") FROM "Table" WHERE "Company" = 'piraeus bank' AND "Revenues (US$ billion)" < 3.9;