Name the candidates for l. mendel rivers
CREATE TABLE table_1341930_40 (
    candidates VARCHAR,
    incumbent VARCHAR
)
SELECT COUNT(candidates) FROM table_1341930_40 WHERE incumbent = "L. Mendel Rivers"
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: Name the candidates for l. mendel rivers ### Input: CREATE TABLE table_1341930_40 (
    candidates VARCHAR,
    incumbent VARCHAR
) ### Response: SELECT COUNT(candidates) FROM table_1341930_40 WHERE incumbent = "L. Mendel Rivers"