Table schema:
CREATE TABLE table_name_56 (gold INTEGER, total VARCHAR, rank VARCHAR, bronze VARCHAR, silver VARCHAR)

Question: What is the average gold medals for countries with more than 0 bronze, more than 0 silver, rank over 2 and total over 3?
SQL: SELECT AVG(gold) FROM table_name_56 WHERE bronze > 0 AND silver > 0 AND rank > 2 AND total > 3