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SELECT Hackers.hacker_id,Hackers.name FROM Hackers,
(
    SELECT Submissions.hacker_id AS hid, COUNT(Submissions.hacker_id) as hct from Submissions, Challenges, Difficulty
    WHERE Submissions.challenge_id = Challenges.challenge_id
    AND Challenges.difficulty_level = Difficulty.difficulty_level
    AND Submissions.score = Difficulty.score
    GROUP BY Submissions.hacker_id
) CAL
WHERE Hackers.hacker_id = CAL.hid AND CAL.hct > 1 ORDER BY CAL.hct DESC, Hackers.hacker_id ASC;