what countries competed in the 2012-13 fis snowboard world cup?
canada, united states, austria, japan, italy, france, australia, norway, slovenia, finland, germany, russia, switzerland, china, poland, czech republic, belgium, netherlands, spain, bulgaria, great britain, sweden
of those countries, which won at least one silver medal?
canada, united states, austria, japan, italy, france, australia, norway, slovenia, finland, germany, switzerland, china, poland, netherlands
of the remaining countries, which won at least five silver medals?
canada, united states, austria, italy, switzerland
of those countries, who won the most silver medals?
austria