How many districts have John C. Calhoun as the incumbent?
CREATE TABLE table_2668352_16 (
    district VARCHAR,
    incumbent VARCHAR
)
SELECT COUNT(district) FROM table_2668352_16 WHERE incumbent = "John C. Calhoun"
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 many districts have John C. Calhoun as the incumbent? ### Input: CREATE TABLE table_2668352_16 (
    district VARCHAR,
    incumbent VARCHAR
) ### Response: SELECT COUNT(district) FROM table_2668352_16 WHERE incumbent = "John C. Calhoun"