Among the flights departing from John F. Kennedy International, how many of them arrived earlier than scheduled?
departing from refers to ORIGIN; John F. Kennedy International refers to Description = 'New York, NY: John F. Kennedy International'; arrived earlier than scheduled refers to ARR_DELAY < 0;
SELECT SUM(CASE WHEN T2.ARR_DELAY < 0 THEN 1 ELSE 0 END) AS count FROM Airports AS T1 INNER JOIN Airlines AS T2 ON T1.Code = T2.ORIGIN WHERE T1.Description = 'New York, NY: John F. Kennedy International'