How many entries for prothrombin time are there where platelet count is 'decreased or unaffected'?
CREATE TABLE table_1555308_1 (
    prothrombin_time VARCHAR,
    platelet_count VARCHAR
)
SELECT COUNT(prothrombin_time) FROM table_1555308_1 WHERE platelet_count = "Decreased or unaffected"
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 entries for prothrombin time are there where platelet count is 'decreased or unaffected'? ### Input: CREATE TABLE table_1555308_1 (
    prothrombin_time VARCHAR,
    platelet_count VARCHAR
) ### Response: SELECT COUNT(prothrombin_time) FROM table_1555308_1 WHERE platelet_count = "Decreased or unaffected"