SELECT
    top 1
    CONCAT(f0.from_city, COALESCE('-' + f0.to_city, ''), COALESCE('-' + f1.to_city, ''), COALESCE('-' + f2.to_city, ''),
           COALESCE('-' + f3.to_city, '')) AS route
  ,
    (f0.duration + ISNULL(f1.duration, 0) + ISNULL(f2.duration, 0) + ISNULL(f3.duration, 0)) AS total_duration
    FROM
        flights f0
            LEFT JOIN flights f1
                      ON f1.from_city = f0.to_city AND f1.to_city NOT IN (f0.from_city)
            LEFT JOIN flights f2
                      ON f2.from_city = f1.to_city AND f2.to_city NOT IN (f0.from_city, f1.from_city)
            LEFT JOIN flights f3
                      ON f3.from_city = f2.to_city AND f3.to_city NOT IN (f0.from_city, f1.from_city, f2.from_city)
    WHERE
          f0.from_city = 'Kharkiv'
      AND 'Vancouver' IN (f0.to_city, f1.to_city, f2.to_city, f3.to_city)
    ORDER BY total_duration, route