WITH AvailableSeats AS (
    SELECT
        LINE_ID,
        SEAT_NO AS SEAT_F,
        LEAD(SEAT_NO, 2) OVER(PARTITION BY LINE_ID ORDER BY SEAT_NO) AS SEAT_T,
        RSV_STATUS
    FROM
        SEAT_RESERVE
    WHERE
        RSV_STATUS = '0'
)
SELECT
    LINE_ID AS LINE,
    SEAT_F,
    SEAT_T
FROM
    AvailableSeats
WHERE
    SEAT_T = SEAT_F + 2
ORDER BY
    LINE_ID DESC, SEAT_F ASC;