How many characters were portrayed by the informant of don flack?
CREATE TABLE table_16567 (
    "Character" text,
    "Portrayed by" text,
    "Relationship" text,
    "First appearance" text,
    "Last appearance" text
)
SELECT COUNT("Portrayed by") FROM table_16567 WHERE "Relationship" = 'Informant of Don Flack'
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 characters were portrayed by the informant of don flack? ### Input: CREATE TABLE table_16567 (
    "Character" text,
    "Portrayed by" text,
    "Relationship" text,
    "First appearance" text,
    "Last appearance" text
) ### Response: SELECT COUNT("Portrayed by") FROM table_16567 WHERE "Relationship" = 'Informant of Don Flack'