SELECT y.hacker_id, name, soma
 FROM(
    SELECT hacker_id, SUM(max_score) as soma
    FROM(
        SELECT hacker_id, challenge_id, max(score) as max_score
        FROM Submissions
        GROUP BY hacker_id, challenge_id
    ) as x
    GROUP BY hacker_id
) as y
INNER JOIN Hackers
ON Hackers.hacker_id = y.hacker_id
WHERE soma <> 0
ORDER BY soma DESC, hacker_id ASC