How long does the one that stars with son bou of middle difficulty, and on a stage number larger than 13 last?
CREATE TABLE table_43728 (
    "Stage" real,
    "Start" text,
    "Arrival" text,
    "Duration" text,
    "Difficulty" text
)
SELECT "Duration" FROM table_43728 WHERE "Stage" > '13' AND "Difficulty" = 'middle' AND "Start" = 'son bou'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: How long does the one that stars with son bou of middle difficulty, and on a stage number larger than 13 last? ### Input: CREATE TABLE table_43728 (
    "Stage" real,
    "Start" text,
    "Arrival" text,
    "Duration" text,
    "Difficulty" text
) ### Response: SELECT "Duration" FROM table_43728 WHERE "Stage" > '13' AND "Difficulty" = 'middle' AND "Start" = 'son bou'