select h.hacker_id, h.name
from Hackers h, Submissions s, Challenges c, Difficulty d
where h.hacker_id = s.hacker_id
    and s.challenge_id = c.challenge_id
    and c.difficulty_level = d.difficulty_level
    and s.score = d.score
group by h.hacker_id, h.name
having count(h.hacker_id) > 1
order by count(h.hacker_id) DESC, h.hacker_id ASC