WITH cte AS
(
    SELECT
        MAX(LAT_N) AS max_ltn,
        MIN(LAT_N) AS min_ltn,
        MAX(LONG_W) AS max_lgw,
        MIN(LONG_W) AS min_lgw
    FROM
        STATION
)

SELECT
    ROUND(
        SQRT(((max_ltn - min_ltn) * (max_ltn - min_ltn)) +
             ((max_lgw - min_lgw) * (max_lgw - min_lgw))), 4
        )
FROM
    cte