Which Grid has Laps of 24, and a Rider of marco melandri?
CREATE TABLE table_45956 (
    "Rider" text,
    "Manufacturer" text,
    "Laps" real,
    "Time" text,
    "Grid" real
)
SELECT SUM("Grid") FROM table_45956 WHERE "Laps" = '24' AND "Rider" = 'marco melandri'
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: Which Grid has Laps of 24, and a Rider of marco melandri? ### Input: CREATE TABLE table_45956 (
    "Rider" text,
    "Manufacturer" text,
    "Laps" real,
    "Time" text,
    "Grid" real
) ### Response: SELECT SUM("Grid") FROM table_45956 WHERE "Laps" = '24' AND "Rider" = 'marco melandri'