user: Question: How many gold medals for bulgaria (bul) with 2 silvers and a less than 18 rank?
Columns: ['Rank', 'Nation', 'Gold', 'Silver', 'Bronze', 'Total']
Types: ['real', 'text', 'real', 'real', 'real', 'real']
Sample row: [1.0, 'Soviet Union (URS)', 39.0, 38.0, 17.0, 94.0]
SQL:

assistant: SELECT SUM("Gold") FROM "Table" WHERE "Silver" = 2.0 AND "Nation" = 'bulgaria (bul)' AND "Rank" < 18.0;