On how many different dates was event 1 Suspension Bridge?
CREATE TABLE table_21433 (
    "Episode Number" real,
    "Air Date" text,
    "Event 1" text,
    "Event 2" text,
    "Event 3" text,
    "Event 4" text
)
SELECT COUNT("Air Date") FROM table_21433 WHERE "Event 1" = 'Suspension Bridge'
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: On how many different dates was event 1 Suspension Bridge? ### Input: CREATE TABLE table_21433 (
    "Episode Number" real,
    "Air Date" text,
    "Event 1" text,
    "Event 2" text,
    "Event 3" text,
    "Event 4" text
) ### Response: SELECT COUNT("Air Date") FROM table_21433 WHERE "Event 1" = 'Suspension Bridge'